Add .NET 10 target and make use of C#14 extension members (#1672)

* Add .NET 10 target

* fix IDE0031

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/style-rules/ide0031

* fix ca5399

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca5399

* fix ca1515

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1515

* fix ca2002

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca2002

* fix ca1508

new false positives.

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1508

* fix ca2000

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca2000

* fix ca2025

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca2025

* fix ca1849

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1849

* fix Reverse() overloads

because of https://learn.microsoft.com/en-us/dotnet/core/compatibility/core-libraries/10.0/csharp-overload-resolution

* supress CA2002

* Use extension members for ThrowHelpers

* use extension members for CryptoAbstractions

* use extension member for DateTime.UnixEpoch

* use extension members for string.Join etc

* use extension members for Convert.To/FromHexString

* disable CA1508

* Update .NET 10 RC2

* Workaround Build Regression in .NET 10 RC2

https://github.com/dotnet/sdk/issues/51265

* suppress new warnings introduced by merge

* Update to .NET 10 final release

* Revert "Workaround Build Regression in .NET 10 RC2"

This is fixed in the final release.

This reverts commit 5a59ac9aa8.

* fix new warnings with MSTest 4 + .NET 10

* use same Randomizer instance

* disable CA2000

* reduce CA1849 suppressions

and disable duplicate S6966

* disable preview analyzers

reverts 6c3c06d95a

.editorconfig

@@ -177,7 +177,7 @@ dotnet_diagnostic.S2699.severity = none
 # S2930: "IDisposables" should be disposed
 # https://rules.sonarsource.com/csharp/RSPEC-2930/
 #
-# Duplicate of CA2000.
+# too noisy.
 dotnet_diagnostic.S2930.severity = none
 
 # S2933: Fields that are only assigned in the constructor should be "readonly"
@@ -344,6 +344,10 @@ dotnet_diagnostic.S5659.severity = none
 # https://rules.sonarsource.com/csharp/RSPEC-5773/
 dotnet_diagnostic.S4581.severity = none
 
+# S6966: Awaitable method should be used
+# Duplicate of CA1849
+dotnet_diagnostic.S6966.severity = none
+
 #### StyleCop rules ####
 
 # SA1003: Symbols must be spaced correctly
@@ -683,6 +687,10 @@ dotnet_diagnostic.CA1305.severity = none
 # https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1309
 dotnet_diagnostic.CA1309.severity = none
 
+# CA1508: Avoid dead conditional code
+# Too many false positives.
+dotnet_diagnostic.CA1508.severity = none
+
 # CA1510: Use ArgumentNullException throw helper
 #
 # This is only available in .NET 6.0 and higher. We'd need to use conditional compilation to only
@@ -726,6 +734,14 @@ dotnet_diagnostic.CA1848.severity = silent
 # By default, this diagnostic is only reported for private members.
 dotnet_code_quality.CA1859.api_surface = private,internal
 
+# CA1873: Evaluation of this argument may be expensive and unnecessary if logging is disabled
+dotnet_diagnostic.CA1873.severity = suggestion
+
+# CA2000: Dispose objects before losing scope
+#
+# too noisy.
+dotnet_diagnostic.CA2000.severity = suggestion
+
 # CA2208: Instantiate argument exceptions correctly
 # https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca2208
 #

.github/workflows/build.yml

@@ -18,33 +18,33 @@ jobs:
       uses: actions/setup-dotnet@v5
 
     - name: Build Unit Tests .NET
-      run: dotnet build -f net9.0 test/Renci.SshNet.Tests/
+      run: dotnet build -f net10.0 test/Renci.SshNet.Tests/
 
     - name: Build IntegrationTests .NET
-      run: dotnet build -f net9.0 test/Renci.SshNet.IntegrationTests/
+      run: dotnet build -f net10.0 test/Renci.SshNet.IntegrationTests/
 
     - name: Run Unit Tests .NET
       run: |
         dotnet test \
-          -f net9.0 \
+          -f net10.0 \
           --no-build \
           --logger "console;verbosity=normal" \
           --logger GitHubActions \
           -p:CollectCoverage=true \
           -p:CoverletOutputFormat=cobertura \
-          -p:CoverletOutput=../../coverlet/linux_unit_test_net_9_coverage.xml \
+          -p:CoverletOutput=../../coverlet/linux_unit_test_net_10_coverage.xml \
           test/Renci.SshNet.Tests/
 
     - name: Run Integration Tests .NET
       run: |
         dotnet test \
-          -f net9.0 \
+          -f net10.0 \
           --no-build \
           --logger "console;verbosity=normal" \
           --logger GitHubActions \
           -p:CollectCoverage=true \
           -p:CoverletOutputFormat=cobertura \
-          -p:CoverletOutput=../../coverlet/linux_integration_test_net_9_coverage.xml \
+          -p:CoverletOutput=../../coverlet/linux_integration_test_net_10_coverage.xml \
           test/Renci.SshNet.IntegrationTests/
 
     - name: Archive Coverlet Results
@@ -82,13 +82,13 @@ jobs:
     - name: Run Unit Tests .NET
       run: |
         dotnet test `
-          -f net9.0 `
+          -f net10.0 `
           --no-build `
           --logger "console;verbosity=normal" `
           --logger GitHubActions `
           -p:CollectCoverage=true `
           -p:CoverletOutputFormat=cobertura `
-          -p:CoverletOutput=../../coverlet/windows_unit_test_net_9_coverage.xml `
+          -p:CoverletOutput=../../coverlet/windows_unit_test_net_10_coverage.xml `
           test/Renci.SshNet.Tests/
 
     - name: Run Unit Tests .NET Framework
@@ -173,7 +173,7 @@ jobs:
     - name: Run Integration Tests .NET
       run:
         dotnet test `
-          -f net9.0 `
+          -f net10.0 `
           --logger "console;verbosity=normal" `
           --logger GitHubActions `
           -p:CollectCoverage=true `

Directory.Build.props

@@ -23,7 +23,6 @@
     -->
   <PropertyGroup>
     <EnableNETAnalyzers>true</EnableNETAnalyzers>
-    <AnalysisLevel>preview-All</AnalysisLevel>
     <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
   </PropertyGroup>
 

Directory.Packages.props

@@ -13,7 +13,7 @@
     <!-- Should stay on LTS .NET releases. -->
     <PackageVersion Include="Microsoft.Bcl.Cryptography" Version="10.0.0" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.3" />
-    <PackageVersion Include="Microsoft.Extensions.Logging.Console" Version="9.0.9" />
+    <PackageVersion Include="Microsoft.Extensions.Logging.Console" Version="10.0.0" />
     <PackageVersion Include="MSTest" Version="4.0.2" />
     <PackageVersion Include="Moq" Version="4.20.72" />
     <PackageVersion Include="Nerdbank.GitVersioning" Version="3.7.115" />

global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "9.0.300",
+    "version": "10.0.100",
     "rollForward": "latestFeature"
   }
 }

src/Renci.SshNet/Abstractions/ConvertExtensions.cs

@@ -0,0 +1,34 @@
+#nullable enable
+#if !NET
+using System.Text;
+#endif
+
+namespace System
+{
+    internal static class ConvertExtensions
+    {
+        extension(Convert)
+        {
+#if !NET
+            public static byte[] FromHexString(string s)
+            {
+                return Org.BouncyCastle.Utilities.Encoders.Hex.Decode(s);
+            }
+
+            public static string ToHexString(byte[] inArray)
+            {
+                ArgumentNullException.ThrowIfNull(inArray);
+
+                var builder = new StringBuilder(inArray.Length * 2);
+
+                foreach (var b in inArray)
+                {
+                    builder.Append(b.ToString("X2"));
+                }
+
+                return builder.ToString();
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/CryptoAbstraction.cs

@@ -7,80 +7,8 @@ namespace Renci.SshNet.Abstractions
 {
     internal static class CryptoAbstraction
     {
-        private static readonly RandomNumberGenerator Randomizer = RandomNumberGenerator.Create();
+        internal static readonly RandomNumberGenerator Randomizer = RandomNumberGenerator.Create();
 
         internal static readonly SecureRandom SecureRandom = new SecureRandom(new CryptoApiRandomGenerator(Randomizer));
-
-        /// <summary>
-        /// Generates a <see cref="byte"/> array of the specified length, and fills it with a
-        /// cryptographically strong random sequence of values.
-        /// </summary>
-        /// <param name="length">The length of the array generate.</param>
-        public static byte[] GenerateRandom(int length)
-        {
-            var random = new byte[length];
-            Randomizer.GetBytes(random);
-            return random;
-        }
-
-        public static byte[] HashMD5(byte[] source)
-        {
-#if NET
-            return MD5.HashData(source);
-#else
-            using (var md5 = MD5.Create())
-            {
-                return md5.ComputeHash(source);
-            }
-#endif
-        }
-
-        public static byte[] HashSHA1(byte[] source)
-        {
-#if NET
-            return SHA1.HashData(source);
-#else
-            using (var sha1 = SHA1.Create())
-            {
-                return sha1.ComputeHash(source);
-            }
-#endif
-        }
-
-        public static byte[] HashSHA256(byte[] source)
-        {
-#if NET
-            return SHA256.HashData(source);
-#else
-            using (var sha256 = SHA256.Create())
-            {
-                return sha256.ComputeHash(source);
-            }
-#endif
-        }
-
-        public static byte[] HashSHA384(byte[] source)
-        {
-#if NET
-            return SHA384.HashData(source);
-#else
-            using (var sha384 = SHA384.Create())
-            {
-                return sha384.ComputeHash(source);
-            }
-#endif
-        }
-
-        public static byte[] HashSHA512(byte[] source)
-        {
-#if NET
-            return SHA512.HashData(source);
-#else
-            using (var sha512 = SHA512.Create())
-            {
-                return sha512.ComputeHash(source);
-            }
-#endif
-        }
     }
 }

src/Renci.SshNet/Abstractions/DateTimeExtensions.cs

@@ -0,0 +1,19 @@
+#nullable enable
+namespace System
+{
+    internal static class DateTimeExtensions
+    {
+        extension(DateTime)
+        {
+#if !NET
+            public static DateTime UnixEpoch
+            {
+                get
+                {
+                    return new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
+                }
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/MD5Extensions.cs

@@ -0,0 +1,19 @@
+#nullable enable
+namespace System.Security.Cryptography
+{
+    internal static class MD5Extensions
+    {
+        extension(MD5)
+        {
+#if !NET
+            public static byte[] HashData(byte[] source)
+            {
+                using (var md5 = MD5.Create())
+                {
+                    return md5.ComputeHash(source);
+                }
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/RandomNumberGeneratorExtensions.cs

@@ -0,0 +1,22 @@
+#nullable enable
+#if !NET
+using Renci.SshNet.Abstractions;
+#endif
+
+namespace System.Security.Cryptography
+{
+    internal static class RandomNumberGeneratorExtensions
+    {
+        extension(RandomNumberGenerator)
+        {
+#if !NET
+            public static byte[] GetBytes(int length)
+            {
+                var random = new byte[length];
+                CryptoAbstraction.Randomizer.GetBytes(random);
+                return random;
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/SHA1Extensions.cs

@@ -0,0 +1,18 @@
+namespace System.Security.Cryptography
+{
+    internal static class SHA1Extensions
+    {
+        extension(SHA1)
+        {
+#if !NET
+            public static byte[] HashData(byte[] source)
+            {
+                using (var sha1 = SHA1.Create())
+                {
+                    return sha1.ComputeHash(source);
+                }
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/SHA256Extensions.cs

@@ -0,0 +1,19 @@
+#nullable enable
+namespace System.Security.Cryptography
+{
+    internal static class SHA256Extensions
+    {
+        extension(SHA256)
+        {
+#if !NET
+            public static byte[] HashData(byte[] source)
+            {
+                using (var sha256 = SHA256.Create())
+                {
+                    return sha256.ComputeHash(source);
+                }
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/SHA384Extensions.cs

@@ -0,0 +1,19 @@
+#nullable enable
+namespace System.Security.Cryptography
+{
+    internal static class SHA384Extensions
+    {
+        extension(SHA384)
+        {
+#if !NET
+            public static byte[] HashData(byte[] source)
+            {
+                using (var sha384 = SHA384.Create())
+                {
+                    return sha384.ComputeHash(source);
+                }
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/SHA512Extensions.cs

@@ -0,0 +1,19 @@
+#nullable enable
+namespace System.Security.Cryptography
+{
+    internal static class SHA512Extensions
+    {
+        extension(SHA512)
+        {
+#if !NET
+            public static byte[] HashData(byte[] source)
+            {
+                using (var sha512 = SHA512.Create())
+                {
+                    return sha512.ComputeHash(source);
+                }
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/StringExtensions.cs

@@ -0,0 +1,35 @@
+#nullable enable
+#if NETSTANDARD2_0 || NETFRAMEWORK
+using System.Collections.Generic;
+#endif
+
+namespace System
+{
+    internal static class StringExtensions
+    {
+        extension(string text)
+        {
+#if NETSTANDARD2_0 || NETFRAMEWORK
+            public static string Join(char separator, params string?[] value)
+            {
+                return string.Join(separator.ToString(), value);
+            }
+
+            public static string Join(char separator, IEnumerable<string?> value)
+            {
+                return string.Join(separator.ToString(), value);
+            }
+
+            public static string Join(char separator, string?[] value, int startIndex, int count)
+            {
+                return string.Join(separator.ToString(), value, startIndex, count);
+            }
+
+            public int IndexOf(char value, StringComparison comparisonType)
+            {
+                return text.IndexOf(value.ToString(), comparisonType);
+            }
+#endif
+        }
+    }
+}

src/Renci.SshNet/Abstractions/ThreadAbstraction.cs

@@ -2,8 +2,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet.Abstractions
 {
     internal static class ThreadAbstraction
@@ -18,7 +16,7 @@ namespace Renci.SshNet.Abstractions
         /// </returns>
         public static Task ExecuteThreadLongRunning(Action action)
         {
-            ThrowHelper.ThrowIfNull(action);
+            ArgumentNullException.ThrowIfNull(action);
 
             return Task.Factory.StartNew(action,
                                          CancellationToken.None,
@@ -32,7 +30,7 @@ namespace Renci.SshNet.Abstractions
         /// <param name="action">The action to execute.</param>
         public static void ExecuteThread(Action action)
         {
-            ThrowHelper.ThrowIfNull(action);
+            ArgumentNullException.ThrowIfNull(action);
 
             _ = ThreadPool.QueueUserWorkItem(o => action());
         }

src/Renci.SshNet/Abstractions/ThrowExtensions.cs

@@ -0,0 +1,94 @@
+#nullable enable
+#if !NET
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
+
+namespace System
+{
+    internal static class ThrowExtensions
+    {
+        extension(ObjectDisposedException)
+        {
+            public static void ThrowIf(bool condition, object instance)
+            {
+                if (condition)
+                {
+                    Throw(instance);
+
+                    static void Throw(object? instance)
+                    {
+                        throw new ObjectDisposedException(instance?.GetType().FullName);
+                    }
+                }
+            }
+        }
+
+        extension(ArgumentNullException)
+        {
+            public static void ThrowIfNull([NotNull] object? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
+            {
+                if (argument is null)
+                {
+                    ThrowArgumentNullException(paramName);
+                }
+
+                [DoesNotReturn]
+                static void ThrowArgumentNullException(string? paramName)
+                {
+                    throw new ArgumentNullException(paramName);
+                }
+            }
+        }
+
+        extension(ArgumentException)
+        {
+            public static void ThrowIfNullOrWhiteSpace([NotNull] string? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
+            {
+                if (string.IsNullOrWhiteSpace(argument))
+                {
+                    Throw(argument, paramName);
+
+                    [DoesNotReturn]
+                    static void Throw(string? argument, string? paramName)
+                    {
+                        ThrowIfNull(argument, paramName);
+                        throw new ArgumentException("The value cannot be an empty string or composed entirely of whitespace.", paramName);
+                    }
+                }
+            }
+
+            public static void ThrowIfNullOrEmpty([NotNull] string? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
+            {
+                if (string.IsNullOrEmpty(argument))
+                {
+                    Throw(argument, paramName);
+
+                    [DoesNotReturn]
+                    static void Throw(string? argument, string? paramName)
+                    {
+                        ThrowIfNull(argument, paramName);
+                        throw new ArgumentException("The value cannot be an empty string.", paramName);
+                    }
+                }
+            }
+        }
+
+        extension(ArgumentOutOfRangeException)
+        {
+            public static void ThrowIfNegative(long value, [CallerArgumentExpression(nameof(value))] string? paramName = null)
+            {
+                if (value < 0)
+                {
+                    Throw(value, paramName);
+
+                    [DoesNotReturn]
+                    static void Throw(long value, string? paramName)
+                    {
+                        throw new ArgumentOutOfRangeException(paramName, value, "Value must be non-negative.");
+                    }
+                }
+            }
+        }
+    }
+}
+#endif

src/Renci.SshNet/AuthenticationMethod.cs

@@ -1,7 +1,5 @@
 using System;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet
 {
     /// <summary>
@@ -36,7 +34,7 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentException"><paramref name="username"/> is whitespace or <see langword="null"/>.</exception>
         protected AuthenticationMethod(string username)
         {
-            ThrowHelper.ThrowIfNullOrWhiteSpace(username);
+            ArgumentException.ThrowIfNullOrWhiteSpace(username);
 
             Username = username;
         }

src/Renci.SshNet/BaseClient.cs

@@ -186,8 +186,8 @@ namespace Renci.SshNet
         /// </remarks>
         private protected BaseClient(ConnectionInfo connectionInfo, bool ownsConnectionInfo, IServiceFactory serviceFactory)
         {
-            ThrowHelper.ThrowIfNull(connectionInfo);
-            ThrowHelper.ThrowIfNull(serviceFactory);
+            ArgumentNullException.ThrowIfNull(connectionInfo);
+            ArgumentNullException.ThrowIfNull(serviceFactory);
 
             _connectionInfo = connectionInfo;
             _ownsConnectionInfo = ownsConnectionInfo;
@@ -467,7 +467,7 @@ namespace Renci.SshNet
         /// <exception cref="ObjectDisposedException">The current instance is disposed.</exception>
         protected void CheckDisposed()
         {
-            ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+            ObjectDisposedException.ThrowIf(_isDisposed, this);
         }
 
         /// <summary>

src/Renci.SshNet/ClientAuthentication.cs

@@ -52,8 +52,8 @@ namespace Renci.SshNet
         /// <exception cref="SshAuthenticationException">Failed to authenticate the client.</exception>
         public void Authenticate(IConnectionInfoInternal connectionInfo, ISession session)
         {
-            ThrowHelper.ThrowIfNull(connectionInfo);
-            ThrowHelper.ThrowIfNull(session);
+            ArgumentNullException.ThrowIfNull(connectionInfo);
+            ArgumentNullException.ThrowIfNull(session);
 
             session.RegisterMessage("SSH_MSG_USERAUTH_FAILURE");
             session.RegisterMessage("SSH_MSG_USERAUTH_SUCCESS");
@@ -105,12 +105,7 @@ namespace Renci.SshNet
             {
                 authenticationException = new SshAuthenticationException(string.Format(CultureInfo.InvariantCulture,
                                                                                        "No suitable authentication method found to complete authentication ({0}).",
-#if NET
-                                                                                       string.Join(',', allowedAuthenticationMethods)))
-#else
-                                                                                       string.Join(",", allowedAuthenticationMethods)))
-#endif
-                ;
+                                                                                       string.Join(',', allowedAuthenticationMethods)));
                 return false;
             }
 

src/Renci.SshNet/Common/ChannelDataEventArgs.cs

@@ -16,7 +16,7 @@ namespace Renci.SshNet.Common
         public ChannelDataEventArgs(uint channelNumber, ArraySegment<byte> data)
             : base(channelNumber)
         {
-            ThrowHelper.ThrowIfNull(data.Array);
+            ArgumentNullException.ThrowIfNull(data.Array);
 
             Data = data;
         }

src/Renci.SshNet/Common/ChannelInputStream.cs

@@ -106,7 +106,7 @@ namespace Renci.SshNet.Common
 #endif
             ValidateBufferArguments(buffer, offset, count);
 
-            ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+            ObjectDisposedException.ThrowIf(_isDisposed, this);
 
             if (count == 0)
             {

src/Renci.SshNet/Common/ChannelRequestEventArgs.cs

@@ -16,7 +16,7 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentNullException"><paramref name="info"/> is <see langword="null"/>.</exception>
         public ChannelRequestEventArgs(RequestInfo info)
         {
-            ThrowHelper.ThrowIfNull(info);
+            ArgumentNullException.ThrowIfNull(info);
 
             Info = info;
         }

src/Renci.SshNet/Common/Extensions.cs

@@ -1,5 +1,7 @@
 using System;
+#if !NET
 using System.Collections.Generic;
+#endif
 using System.Globalization;
 #if !NET
 using System.IO;
@@ -193,7 +195,7 @@ namespace Renci.SshNet.Common
         /// </remarks>
         public static byte[] Take(this byte[] value, int offset, int count)
         {
-            ThrowHelper.ThrowIfNull(value);
+            ArgumentNullException.ThrowIfNull(value);
 
             if (count == 0)
             {
@@ -225,7 +227,7 @@ namespace Renci.SshNet.Common
         /// </remarks>
         public static byte[] Take(this byte[] value, int count)
         {
-            ThrowHelper.ThrowIfNull(value);
+            ArgumentNullException.ThrowIfNull(value);
 
             if (count == 0)
             {
@@ -244,8 +246,8 @@ namespace Renci.SshNet.Common
 
         public static bool IsEqualTo(this byte[] left, byte[] right)
         {
-            ThrowHelper.ThrowIfNull(left);
-            ThrowHelper.ThrowIfNull(right);
+            ArgumentNullException.ThrowIfNull(left);
+            ArgumentNullException.ThrowIfNull(right);
 
             return left.AsSpan().SequenceEqual(right);
         }
@@ -259,7 +261,7 @@ namespace Renci.SshNet.Common
         /// </returns>
         public static byte[] TrimLeadingZeros(this byte[] value)
         {
-            ThrowHelper.ThrowIfNull(value);
+            ArgumentNullException.ThrowIfNull(value);
 
             for (var i = 0; i < value.Length; i++)
             {
@@ -329,13 +331,6 @@ namespace Renci.SshNet.Common
             return socket.Connected;
         }
 
-        internal static string Join(this IEnumerable<string> values, string separator)
-        {
-            // Used to avoid analyzers asking to "use an overload with a char parameter"
-            // which is not available on all targets.
-            return string.Join(separator, values);
-        }
-
 #if !NET
         internal static bool TryAdd<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key, TValue value)
         {

src/Renci.SshNet/Common/HostKeyEventArgs.cs

@@ -1,7 +1,7 @@
 #nullable enable
 using System;
+using System.Security.Cryptography;
 
-using Renci.SshNet.Abstractions;
 using Renci.SshNet.Security;
 
 namespace Renci.SshNet.Common
@@ -97,16 +97,16 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentNullException"><paramref name="host"/> is <see langword="null"/>.</exception>
         public HostKeyEventArgs(KeyHostAlgorithm host)
         {
-            ThrowHelper.ThrowIfNull(host);
+            ArgumentNullException.ThrowIfNull(host);
 
             CanTrust = true;
             HostKey = host.KeyData.GetBytes();
             HostKeyName = host.Name;
             KeyLength = host.Key.KeyLength;
 
-            _lazyFingerPrint = new Lazy<byte[]>(() => CryptoAbstraction.HashMD5(HostKey));
+            _lazyFingerPrint = new Lazy<byte[]>(() => MD5.HashData(HostKey));
 
-            _lazyFingerPrintSHA256 = new Lazy<string>(() => Convert.ToBase64String(CryptoAbstraction.HashSHA256(HostKey)).TrimEnd('='));
+            _lazyFingerPrintSHA256 = new Lazy<string>(() => Convert.ToBase64String(SHA256.HashData(HostKey)).TrimEnd('='));
 
             _lazyFingerPrintMD5 = new Lazy<string>(() =>
                 {

src/Renci.SshNet/Common/Lock.cs

@@ -7,7 +7,9 @@ namespace Renci.SshNet.Common
     {
         public bool TryEnter()
         {
+#pragma warning disable CA2002 // Do not lock on objects with weak identity
             return Monitor.TryEnter(this);
+#pragma warning restore CA2002 // Do not lock on objects with weak identity
         }
 
         public void Exit()

src/Renci.SshNet/Common/PacketDump.cs

@@ -14,8 +14,8 @@ namespace Renci.SshNet.Common
 
         public static string Create(byte[] data, int indentLevel)
         {
-            ThrowHelper.ThrowIfNull(data);
-            ThrowHelper.ThrowIfNegative(indentLevel);
+            ArgumentNullException.ThrowIfNull(data);
+            ArgumentOutOfRangeException.ThrowIfNegative(indentLevel);
 
             const int lineWidth = 16;
 

src/Renci.SshNet/Common/PipeStream.cs

@@ -123,7 +123,7 @@ namespace Renci.SshNet.Common
         {
             Debug.Assert(Monitor.IsEntered(_sync));
 
-            ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+            ObjectDisposedException.ThrowIf(_disposed, this);
 
             _buffer.EnsureAvailableSpace(buffer.Length);
 

src/Renci.SshNet/Common/PortForwardEventArgs.cs

@@ -17,7 +17,7 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port" /> is not within <see cref="IPEndPoint.MinPort" /> and <see cref="IPEndPoint.MaxPort" />.</exception>
         internal PortForwardEventArgs(string host, uint port)
         {
-            ThrowHelper.ThrowIfNull(host);
+            ArgumentNullException.ThrowIfNull(host);
             port.ValidatePort();
 
             OriginatorHost = host;

src/Renci.SshNet/Common/PosixPath.cs

@@ -38,7 +38,7 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentException"><paramref name="path"/> is empty ("").</exception>
         public static PosixPath CreateAbsoluteOrRelativeFilePath(string path)
         {
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             var posixPath = new PosixPath();
 
@@ -92,7 +92,7 @@ namespace Renci.SshNet.Common
         /// </remarks>
         public static string GetFileName(string path)
         {
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             var pathEnd = path.LastIndexOf('/');
             if (pathEnd == -1)
@@ -119,7 +119,7 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentNullException"><paramref name="path"/> is <see langword="null"/>.</exception>
         public static string GetDirectoryName(string path)
         {
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             var pathEnd = path.LastIndexOf('/');
             if (pathEnd == -1)

src/Renci.SshNet/Common/SftpException.cs

@@ -11,7 +11,9 @@ namespace Renci.SshNet.Common
 #if NETFRAMEWORK
     [Serializable]
 #endif
+#pragma warning disable CA1032 // Implement standard exception constructors
     public class SftpException : SshException
+#pragma warning restore CA1032 // Implement standard exception constructors
     {
         /// <summary>
         /// Gets the status code that is associated with this exception.

src/Renci.SshNet/Common/SshData.cs

@@ -91,7 +91,7 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentNullException"><paramref name="data"/> is <see langword="null"/>.</exception>
         public void Load(byte[] data)
         {
-            ThrowHelper.ThrowIfNull(data);
+            ArgumentNullException.ThrowIfNull(data);
 
             LoadInternal(data, 0, data.Length);
         }
@@ -105,7 +105,7 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentNullException"><paramref name="data"/> is <see langword="null"/>.</exception>
         public void Load(byte[] data, int offset, int count)
         {
-            ThrowHelper.ThrowIfNull(data);
+            ArgumentNullException.ThrowIfNull(data);
 
             LoadInternal(data, offset, count);
         }
@@ -386,11 +386,7 @@ namespace Renci.SshNet.Common
         /// <param name="data">name-list data to write.</param>
         protected void Write(string[] data)
         {
-#if NET
             Write(string.Join(',', data), Ascii);
-#else
-            Write(string.Join(",", data), Ascii);
-#endif
         }
 
         /// <summary>

src/Renci.SshNet/Common/SshDataStream.cs

@@ -112,7 +112,7 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentNullException"><paramref name="data"/> is <see langword="null"/>.</exception>
         public void Write(byte[] data)
         {
-            ThrowHelper.ThrowIfNull(data);
+            ArgumentNullException.ThrowIfNull(data);
 
             Write(data, 0, data.Length);
         }
@@ -126,8 +126,8 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentNullException"><paramref name="encoding"/> is <see langword="null"/>.</exception>
         public void Write(string s, Encoding encoding)
         {
-            ThrowHelper.ThrowIfNull(s);
-            ThrowHelper.ThrowIfNull(encoding);
+            ArgumentNullException.ThrowIfNull(s);
+            ArgumentNullException.ThrowIfNull(encoding);
 
 #if NET
             ReadOnlySpan<char> value = s;
@@ -192,7 +192,7 @@ namespace Renci.SshNet.Common
         /// <exception cref="ArgumentNullException"><paramref name="buffer"/> is <see langword="null"/>.</exception>
         public void WriteBinary(byte[] buffer)
         {
-            ThrowHelper.ThrowIfNull(buffer);
+            ArgumentNullException.ThrowIfNull(buffer);
 
             WriteBinary(buffer, 0, buffer.Length);
         }

src/Renci.SshNet/Common/TaskToAsyncResult.cs

@@ -1,6 +1,6 @@
 #pragma warning disable
 #if !NET
-// Copied verbatim from https://github.com/dotnet/runtime/blob/261611930d6b436d7c4395450356b624d903d9bf/src/libraries/Common/src/System/Threading/Tasks/TaskToAsyncResult.cs
+// Copied verbatim from https://github.com/dotnet/runtime/blob/7b2de1e5ed6368c536ee646346e6fd81939e6fe6/src/libraries/Common/src/System/Threading/Tasks/TaskToAsyncResult.cs
 
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
@@ -35,15 +35,7 @@ namespace System.Threading.Tasks
         /// </remarks>
         public static IAsyncResult Begin(Task task, AsyncCallback? callback, object? state)
         {
-#if NET
             ArgumentNullException.ThrowIfNull(task);
-#else
-            if (task is null)
-            {
-                throw new ArgumentNullException(nameof(task));
-            }
-#endif
-
             return new TaskAsyncResult(task, state, callback);
         }
 
@@ -72,14 +64,7 @@ namespace System.Threading.Tasks
         /// <exception cref="ArgumentException"><paramref name="asyncResult"/> was not produced by a call to <see cref="Begin"/>.</exception>
         public static Task Unwrap(IAsyncResult asyncResult)
         {
-#if NET
             ArgumentNullException.ThrowIfNull(asyncResult);
-#else
-            if (asyncResult is null)
-            {
-                throw new ArgumentNullException(nameof(asyncResult));
-            }
-#endif
 
             if ((asyncResult as TaskAsyncResult)?._task is not Task task)
             {
@@ -101,14 +86,7 @@ namespace System.Threading.Tasks
         /// </exception>
         public static Task<TResult> Unwrap<TResult>(IAsyncResult asyncResult)
         {
-#if NET
             ArgumentNullException.ThrowIfNull(asyncResult);
-#else
-            if (asyncResult is null)
-            {
-                throw new ArgumentNullException(nameof(asyncResult));
-            }
-#endif
 
             if ((asyncResult as TaskAsyncResult)?._task is not Task<TResult> task)
             {

src/Renci.SshNet/Common/ThrowHelper.cs

@@ -1,93 +1,19 @@
 #nullable enable
+#if !NET
 using System;
 using System.Diagnostics.CodeAnalysis;
-using System.Runtime.CompilerServices;
 
 namespace Renci.SshNet.Common
 {
     internal static class ThrowHelper
     {
-        public static void ThrowObjectDisposedIf(bool condition, object instance)
-        {
-#if NET
-            ObjectDisposedException.ThrowIf(condition, instance);
-#else
-            if (condition)
-            {
-                Throw(instance);
-
-                static void Throw(object? instance)
-                {
-                    throw new ObjectDisposedException(instance?.GetType().FullName);
-                }
-            }
-#endif
-        }
-
-        public static void ThrowIfNull([NotNull] object? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
-        {
-#if NET
-            ArgumentNullException.ThrowIfNull(argument, paramName);
-#else
-            if (argument is null)
-            {
-                Throw(paramName);
-
-                [DoesNotReturn]
-                static void Throw(string? paramName)
-                {
-                    throw new ArgumentNullException(paramName);
-                }
-            }
-#endif
-        }
-
-        public static void ThrowIfNullOrWhiteSpace([NotNull] string? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
-        {
-#if NET
-            ArgumentException.ThrowIfNullOrWhiteSpace(argument, paramName);
-#else
-            if (string.IsNullOrWhiteSpace(argument))
-            {
-                Throw(argument, paramName);
-
-                [DoesNotReturn]
-                static void Throw(string? argument, string? paramName)
-                {
-                    ThrowIfNull(argument, paramName);
-                    throw new ArgumentException("The value cannot be an empty string or composed entirely of whitespace.", paramName);
-                }
-            }
-#endif
-        }
-
-        public static void ThrowIfNullOrEmpty([NotNull] string? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
-        {
-#if NET
-            ArgumentException.ThrowIfNullOrEmpty(argument, paramName);
-#else
-            if (string.IsNullOrEmpty(argument))
-            {
-                Throw(argument, paramName);
-
-                [DoesNotReturn]
-                static void Throw(string? argument, string? paramName)
-                {
-                    ThrowIfNull(argument, paramName);
-                    throw new ArgumentException("The value cannot be an empty string.", paramName);
-                }
-            }
-#endif
-        }
-
-#if !NET
         // A rough copy of
         // https://github.com/dotnet/runtime/blob/1d1bf92fcf43aa6981804dc53c5174445069c9e4/src/libraries/System.Private.CoreLib/src/System/IO/Stream.cs#L960C13-L974C10
         // for lower targets.
         public static void ValidateBufferArguments(byte[] buffer, int offset, int count)
         {
-            ThrowIfNull(buffer);
-            ThrowIfNegative(offset);
+            ArgumentNullException.ThrowIfNull(buffer);
+            ArgumentOutOfRangeException.ThrowIfNegative(offset);
 
             if ((uint)count > buffer.Length - offset)
             {
@@ -102,24 +28,6 @@ namespace Renci.SshNet.Common
                 }
             }
         }
-#endif
-
-        public static void ThrowIfNegative(long value, [CallerArgumentExpression(nameof(value))] string? paramName = null)
-        {
-#if NET
-            ArgumentOutOfRangeException.ThrowIfNegative(value, paramName);
-#else
-            if (value < 0)
-            {
-                Throw(value, paramName);
-
-                [DoesNotReturn]
-                static void Throw(long value, string? paramName)
-                {
-                    throw new ArgumentOutOfRangeException(paramName, value, "Value must be non-negative.");
-                }
-            }
-#endif
-        }
     }
 }
+#endif

src/Renci.SshNet/Connection/ConnectorBase.cs

@@ -18,7 +18,7 @@ namespace Renci.SshNet.Connection
 
         protected ConnectorBase(ISocketFactory socketFactory, ILoggerFactory loggerFactory)
         {
-            ThrowHelper.ThrowIfNull(socketFactory);
+            ArgumentNullException.ThrowIfNull(socketFactory);
 
             SocketFactory = socketFactory;
             _logger = loggerFactory.CreateLogger(GetType());

src/Renci.SshNet/Connection/SshIdentification.cs

@@ -1,7 +1,5 @@
 using System;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet.Connection
 {
     /// <summary>
@@ -33,8 +31,8 @@ namespace Renci.SshNet.Connection
         /// <exception cref="ArgumentNullException"><paramref name="softwareVersion"/> is <see langword="null"/>.</exception>
         public SshIdentification(string protocolVersion, string softwareVersion, string comments)
         {
-            ThrowHelper.ThrowIfNull(protocolVersion);
-            ThrowHelper.ThrowIfNull(softwareVersion);
+            ArgumentNullException.ThrowIfNull(protocolVersion);
+            ArgumentNullException.ThrowIfNull(softwareVersion);
 
             ProtocolVersion = protocolVersion;
             SoftwareVersion = softwareVersion;

src/Renci.SshNet/ConnectionInfo.cs

@@ -325,17 +325,17 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentException">No <paramref name="authenticationMethods"/> specified.</exception>
         public ConnectionInfo(string host, int port, string username, ProxyTypes proxyType, string proxyHost, int proxyPort, string proxyUsername, string proxyPassword, params AuthenticationMethod[] authenticationMethods)
         {
-            ThrowHelper.ThrowIfNull(host);
+            ArgumentNullException.ThrowIfNull(host);
             port.ValidatePort();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(username);
+            ArgumentException.ThrowIfNullOrWhiteSpace(username);
 
             if (proxyType != ProxyTypes.None)
             {
-                ThrowHelper.ThrowIfNull(proxyHost);
+                ArgumentNullException.ThrowIfNull(proxyHost);
                 proxyPort.ValidatePort();
             }
 
-            ThrowHelper.ThrowIfNull(authenticationMethods);
+            ArgumentNullException.ThrowIfNull(authenticationMethods);
 
             if (authenticationMethods.Length == 0)
             {
@@ -459,7 +459,7 @@ namespace Renci.SshNet
         /// <exception cref="SshAuthenticationException">No suitable authentication method found to complete authentication, or permission denied.</exception>
         internal void Authenticate(ISession session, IServiceFactory serviceFactory)
         {
-            ThrowHelper.ThrowIfNull(serviceFactory);
+            ArgumentNullException.ThrowIfNull(serviceFactory);
 
             IsAuthenticated = false;
             var clientAuthentication = serviceFactory.CreateClientAuthentication();

src/Renci.SshNet/ExpectAction.cs

@@ -1,8 +1,6 @@
 using System;
 using System.Text.RegularExpressions;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet
 {
     /// <summary>
@@ -28,8 +26,8 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="expect"/> or <paramref name="action"/> is <see langword="null"/>.</exception>
         public ExpectAction(Regex expect, Action<string> action)
         {
-            ThrowHelper.ThrowIfNull(expect);
-            ThrowHelper.ThrowIfNull(action);
+            ArgumentNullException.ThrowIfNull(expect);
+            ArgumentNullException.ThrowIfNull(action);
 
             Expect = expect;
             Action = action;
@@ -43,8 +41,8 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="expect"/> or <paramref name="action"/> is <see langword="null"/>.</exception>
         public ExpectAction(string expect, Action<string> action)
         {
-            ThrowHelper.ThrowIfNull(expect);
-            ThrowHelper.ThrowIfNull(action);
+            ArgumentNullException.ThrowIfNull(expect);
+            ArgumentNullException.ThrowIfNull(action);
 
             Expect = new Regex(Regex.Escape(expect));
             Action = action;

src/Renci.SshNet/ForwardedPortDynamic.cs

@@ -130,7 +130,7 @@ namespace Renci.SshNet
         /// <exception cref="ObjectDisposedException">The current instance is disposed.</exception>
         protected override void CheckDisposed()
         {
-            ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+            ObjectDisposedException.ThrowIf(_isDisposed, this);
         }
 
         /// <summary>
@@ -182,9 +182,7 @@ namespace Renci.SshNet
         {
             if (e is null)
             {
-#pragma warning disable CA2000 // Dispose objects before losing scope
                 e = new SocketAsyncEventArgs();
-#pragma warning restore CA2000 // Dispose objects before losing scope
                 e.Completed += AcceptCompleted;
             }
             else

src/Renci.SshNet/ForwardedPortLocal.cs

@@ -91,8 +91,8 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port" /> is greater than <see cref="IPEndPoint.MaxPort" />.</exception>
         public ForwardedPortLocal(string boundHost, uint boundPort, string host, uint port)
         {
-            ThrowHelper.ThrowIfNull(boundHost);
-            ThrowHelper.ThrowIfNull(host);
+            ArgumentNullException.ThrowIfNull(boundHost);
+            ArgumentNullException.ThrowIfNull(host);
 
             boundPort.ValidatePort();
             port.ValidatePort();
@@ -158,7 +158,7 @@ namespace Renci.SshNet
         /// <exception cref="ObjectDisposedException">The current instance is disposed.</exception>
         protected override void CheckDisposed()
         {
-            ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+            ObjectDisposedException.ThrowIf(_isDisposed, this);
         }
 
         /// <summary>
@@ -212,9 +212,7 @@ namespace Renci.SshNet
         {
             if (e is null)
             {
-#pragma warning disable CA2000 // Dispose objects before losing scope
                 e = new SocketAsyncEventArgs();
-#pragma warning restore CA2000 // Dispose objects before losing scope
                 e.Completed += AcceptCompleted;
             }
             else

src/Renci.SshNet/ForwardedPortRemote.cs

@@ -88,8 +88,8 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port" /> is greater than <see cref="IPEndPoint.MaxPort" />.</exception>
         public ForwardedPortRemote(IPAddress boundHostAddress, uint boundPort, IPAddress hostAddress, uint port)
         {
-            ThrowHelper.ThrowIfNull(boundHostAddress);
-            ThrowHelper.ThrowIfNull(hostAddress);
+            ArgumentNullException.ThrowIfNull(boundHostAddress);
+            ArgumentNullException.ThrowIfNull(hostAddress);
 
             boundPort.ValidatePort();
             port.ValidatePort();
@@ -227,7 +227,7 @@ namespace Renci.SshNet
         /// <exception cref="ObjectDisposedException">The current instance is disposed.</exception>
         protected override void CheckDisposed()
         {
-            ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+            ObjectDisposedException.ThrowIf(_isDisposed, this);
         }
 
         private void Session_ChannelOpening(object sender, MessageEventArgs<ChannelOpenMessage> e)

src/Renci.SshNet/MessageEventArgs`1.cs

@@ -1,7 +1,5 @@
 using System;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet
 {
     /// <summary>
@@ -22,7 +20,7 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="message"/> is <see langword="null"/>.</exception>
         public MessageEventArgs(T message)
         {
-            ThrowHelper.ThrowIfNull(message);
+            ArgumentNullException.ThrowIfNull(message);
 
             Message = message;
         }

src/Renci.SshNet/Messages/Authentication/FailureMessage.cs

@@ -55,11 +55,7 @@ namespace Renci.SshNet.Messages.Authentication
             PartialSuccess = ReadBoolean();
             if (PartialSuccess)
             {
-#if NET
                 Message = string.Join(',', AllowedAuthentications);
-#else
-                Message = string.Join(",", AllowedAuthentications);
-#endif
             }
         }
 

src/Renci.SshNet/Messages/Connection/ChannelDataMessage.cs

@@ -1,4 +1,4 @@
-using Renci.SshNet.Common;
+using System;
 
 namespace Renci.SshNet.Messages.Connection
 {
@@ -89,7 +89,7 @@ namespace Renci.SshNet.Messages.Connection
         public ChannelDataMessage(uint localChannelNumber, byte[] data)
             : base(localChannelNumber)
         {
-            ThrowHelper.ThrowIfNull(data);
+            ArgumentNullException.ThrowIfNull(data);
 
             Data = data;
             Offset = 0;
@@ -106,7 +106,7 @@ namespace Renci.SshNet.Messages.Connection
         public ChannelDataMessage(uint localChannelNumber, byte[] data, int offset, int size)
             : base(localChannelNumber)
         {
-            ThrowHelper.ThrowIfNull(data);
+            ArgumentNullException.ThrowIfNull(data);
 
             Data = data;
             Offset = offset;

src/Renci.SshNet/Messages/Connection/ChannelOpen/ChannelOpenMessage.cs

@@ -1,8 +1,6 @@
 using System;
 using System.Globalization;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet.Messages.Connection
 {
     /// <summary>
@@ -106,7 +104,7 @@ namespace Renci.SshNet.Messages.Connection
         /// <exception cref="ArgumentNullException"><paramref name="info"/> is <see langword="null"/>.</exception>
         public ChannelOpenMessage(uint channelNumber, uint initialWindowSize, uint maximumPacketSize, ChannelOpenInfo info)
         {
-            ThrowHelper.ThrowIfNull(info);
+            ArgumentNullException.ThrowIfNull(info);
 
             ChannelType = Ascii.GetBytes(info.ChannelType);
             LocalChannelNumber = channelNumber;

src/Renci.SshNet/Messages/Connection/ChannelRequest/ExecRequestInfo.cs

@@ -1,8 +1,6 @@
 using System;
 using System.Text;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet.Messages.Connection
 {
     /// <summary>
@@ -81,8 +79,8 @@ namespace Renci.SshNet.Messages.Connection
         public ExecRequestInfo(string command, Encoding encoding)
             : this()
         {
-            ThrowHelper.ThrowIfNull(command);
-            ThrowHelper.ThrowIfNull(encoding);
+            ArgumentNullException.ThrowIfNull(command);
+            ArgumentNullException.ThrowIfNull(encoding);
 
             _command = encoding.GetBytes(command);
             Encoding = encoding;

src/Renci.SshNet/Messages/Message.cs

@@ -1,6 +1,6 @@
 using System.IO;
+using System.Security.Cryptography;
 
-using Renci.SshNet.Abstractions;
 using Renci.SshNet.Common;
 using Renci.SshNet.Compression;
 
@@ -83,7 +83,7 @@ namespace Renci.SshNet.Messages
                     var paddingLength = GetPaddingLength(paddingMultiplier, excludePacketLengthFieldWhenPadding ? packetLength - 4 : packetLength);
 
                     // add padding bytes
-                    var paddingBytes = CryptoAbstraction.GenerateRandom(paddingLength);
+                    var paddingBytes = RandomNumberGenerator.GetBytes(paddingLength);
                     sshDataStream.Write(paddingBytes, 0, paddingLength);
 
                     var packetDataLength = GetPacketDataLength(messageLength, paddingLength);
@@ -127,7 +127,7 @@ namespace Renci.SshNet.Messages
                     WriteBytes(sshDataStream);
 
                     // add padding bytes
-                    var paddingBytes = CryptoAbstraction.GenerateRandom(paddingLength);
+                    var paddingBytes = RandomNumberGenerator.GetBytes(paddingLength);
                     sshDataStream.Write(paddingBytes, 0, paddingLength);
 
                     return sshDataStream.ToArray();

src/Renci.SshNet/Messages/Transport/IgnoreMessage.cs

@@ -1,7 +1,5 @@
 using System;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet.Messages.Transport
 {
     /// <summary>
@@ -47,7 +45,7 @@ namespace Renci.SshNet.Messages.Transport
         /// <param name="data">The data.</param>
         public IgnoreMessage(byte[] data)
         {
-            ThrowHelper.ThrowIfNull(data);
+            ArgumentNullException.ThrowIfNull(data);
 
             Data = data;
         }

src/Renci.SshNet/Messages/Transport/KeyExchangeInitMessage.cs

@@ -1,4 +1,4 @@
-using Renci.SshNet.Abstractions;
+using System.Security.Cryptography;
 
 namespace Renci.SshNet.Messages.Transport
 {
@@ -12,7 +12,7 @@ namespace Renci.SshNet.Messages.Transport
         /// </summary>
         public KeyExchangeInitMessage()
         {
-            Cookie = CryptoAbstraction.GenerateRandom(16);
+            Cookie = RandomNumberGenerator.GetBytes(16);
         }
 
         #region Message Properties

src/Renci.SshNet/NetConfClient.cs

@@ -1,6 +1,5 @@
 #nullable enable
 using System;
-using System.Diagnostics.CodeAnalysis;
 using System.Net;
 using System.Threading;
 using System.Xml;
@@ -73,7 +72,6 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="password"/> is <see langword="null"/>.</exception>
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, or <paramref name="username"/> is <see langword="null"/> or contains only whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
-        [SuppressMessage("Microsoft.Reliability", "CA2000:DisposeObjectsBeforeLosingScope", Justification = "Disposed in Dispose(bool) method.")]
         public NetConfClient(string host, int port, string username, string password)
             : this(new PasswordConnectionInfo(host, port, username, password), ownsConnectionInfo: true)
         {
@@ -102,7 +100,6 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="keyFiles"/> is <see langword="null"/>.</exception>
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, -or- <paramref name="username"/> is <see langword="null"/> or contains only whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
-        [SuppressMessage("Microsoft.Reliability", "CA2000:DisposeObjectsBeforeLosingScope", Justification = "Disposed in Dispose(bool) method.")]
         public NetConfClient(string host, int port, string username, params IPrivateKeySource[] keyFiles)
             : this(new PrivateKeyConnectionInfo(host, port, username, keyFiles), ownsConnectionInfo: true)
         {
@@ -299,11 +296,8 @@ namespace Renci.SshNet
 
             if (disposing)
             {
-                if (_netConfSession != null)
-                {
-                    _netConfSession.Dispose();
-                    _netConfSession = null;
-                }
+                _netConfSession?.Dispose();
+                _netConfSession = null;
             }
         }
 

src/Renci.SshNet/Netconf/NetConfSession.cs

@@ -213,17 +213,11 @@ namespace Renci.SshNet.NetConf
 
             if (disposing)
             {
-                if (_serverCapabilitiesConfirmed != null)
-                {
-                    _serverCapabilitiesConfirmed.Dispose();
-                    _serverCapabilitiesConfirmed = null;
-                }
+                _serverCapabilitiesConfirmed?.Dispose();
+                _serverCapabilitiesConfirmed = null;
 
-                if (_rpcReplyReceived != null)
-                {
-                    _rpcReplyReceived.Dispose();
-                    _rpcReplyReceived = null;
-                }
+                _rpcReplyReceived?.Dispose();
+                _rpcReplyReceived = null;
             }
         }
     }

src/Renci.SshNet/NoneAuthenticationMethod.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Threading;
 
-using Renci.SshNet.Common;
 using Renci.SshNet.Messages;
 using Renci.SshNet.Messages.Authentication;
 
@@ -44,7 +43,7 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="session" /> is <see langword="null"/>.</exception>
         public override AuthenticationResult Authenticate(Session session)
         {
-            ThrowHelper.ThrowIfNull(session);
+            ArgumentNullException.ThrowIfNull(session);
 
             session.UserAuthenticationSuccessReceived += Session_UserAuthenticationSuccessReceived;
             session.UserAuthenticationFailureReceived += Session_UserAuthenticationFailureReceived;

src/Renci.SshNet/OrderedDictionary.netstandard.cs

@@ -9,7 +9,9 @@ using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 
+#if !NET
 using Renci.SshNet.Common;
+#endif
 
 namespace Renci.SshNet
 {
@@ -486,8 +488,8 @@ namespace Renci.SshNet
 
             public virtual void CopyTo(T[] array, int arrayIndex)
             {
-                ThrowHelper.ThrowIfNull(array);
-                ThrowHelper.ThrowIfNegative(arrayIndex);
+                ArgumentNullException.ThrowIfNull(array);
+                ArgumentOutOfRangeException.ThrowIfNegative(arrayIndex);
 
                 if (array.Length - arrayIndex < Count)
                 {

src/Renci.SshNet/PasswordAuthenticationMethod.cs

@@ -69,7 +69,7 @@ namespace Renci.SshNet
         public PasswordAuthenticationMethod(string username, byte[] password)
             : base(username)
         {
-            ThrowHelper.ThrowIfNull(password);
+            ArgumentNullException.ThrowIfNull(password);
 
             _password = password;
             _requestMessage = new RequestMessagePassword(ServiceName.Connection, Username, _password);
@@ -85,7 +85,7 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="session" /> is <see langword="null"/>.</exception>
         public override AuthenticationResult Authenticate(Session session)
         {
-            ThrowHelper.ThrowIfNull(session);
+            ArgumentNullException.ThrowIfNull(session);
 
             _session = session;
 

src/Renci.SshNet/PrivateKeyAuthenticationMethod.cs

@@ -42,7 +42,7 @@ namespace Renci.SshNet
         public PrivateKeyAuthenticationMethod(string username, params IPrivateKeySource[] keyFiles)
             : base(username)
         {
-            ThrowHelper.ThrowIfNull(keyFiles);
+            ArgumentNullException.ThrowIfNull(keyFiles);
 
             KeyFiles = new Collection<IPrivateKeySource>(keyFiles);
         }

src/Renci.SshNet/PrivateKeyFile.OpenSSH.cs

@@ -32,7 +32,7 @@ namespace Renci.SshNet
             /// </summary>
             public Key Parse()
             {
-                var keyReader = new SshDataStream(_data);
+                using var keyReader = new SshDataStream(_data);
 
                 // check magic header
                 var authMagic = "openssh-key-v1\0"u8;
@@ -171,7 +171,7 @@ namespace Renci.SshNet
                 // now parse the data we called the private key, it actually contains the public key again
                 // so we need to parse through it to get the private key bytes, plus there's some
                 // validation we need to do.
-                var privateKeyReader = new SshDataStream(privateKeyBytes);
+                using var privateKeyReader = new SshDataStream(privateKeyBytes);
 
                 // check ints should match, they wouldn't match for example if the wrong passphrase was supplied
                 var checkInt1 = (int)privateKeyReader.ReadUInt32();

src/Renci.SshNet/PrivateKeyFile.PKCS1.cs

@@ -42,11 +42,8 @@ namespace Renci.SshNet
                     {
                         throw new SshPassPhraseNullOrEmptyException("Private key is encrypted but passphrase is empty.");
                     }
-#if NET
+
                     var binarySalt = Convert.FromHexString(_salt);
-#else
-                    var binarySalt = Org.BouncyCastle.Utilities.Encoders.Hex.Decode(_salt);
-#endif
                     CipherInfo cipher;
                     switch (_cipherName)
                     {

src/Renci.SshNet/PrivateKeyFile.PuTTY.cs

@@ -9,7 +9,6 @@ using System.Text;
 using Org.BouncyCastle.Crypto.Generators;
 using Org.BouncyCastle.Crypto.Parameters;
 
-using Renci.SshNet.Abstractions;
 using Renci.SshNet.Common;
 using Renci.SshNet.Security;
 using Renci.SshNet.Security.Cryptography.Ciphers;
@@ -72,22 +71,18 @@ namespace Renci.SshNet
                         switch (_version)
                         {
                             case "3":
-                                ThrowHelper.ThrowIfNullOrEmpty(_argon2Type);
-                                ThrowHelper.ThrowIfNullOrEmpty(_argon2Iterations);
-                                ThrowHelper.ThrowIfNullOrEmpty(_argon2Memory);
-                                ThrowHelper.ThrowIfNullOrEmpty(_argon2Parallelism);
-                                ThrowHelper.ThrowIfNullOrEmpty(_argon2Salt);
+                                ArgumentException.ThrowIfNullOrEmpty(_argon2Type);
+                                ArgumentException.ThrowIfNullOrEmpty(_argon2Iterations);
+                                ArgumentException.ThrowIfNullOrEmpty(_argon2Memory);
+                                ArgumentException.ThrowIfNullOrEmpty(_argon2Parallelism);
+                                ArgumentException.ThrowIfNullOrEmpty(_argon2Salt);
 
                                 var keyData = Argon2(
                                     _argon2Type,
                                     Convert.ToInt32(_argon2Iterations),
                                     Convert.ToInt32(_argon2Memory),
                                     Convert.ToInt32(_argon2Parallelism),
-#if NET
                                     Convert.FromHexString(_argon2Salt),
-#else
-                                    Org.BouncyCastle.Utilities.Encoders.Hex.Decode(_argon2Salt),
-#endif
                                     _passPhrase);
 
                                 cipherKey = keyData.Take(32);
@@ -103,7 +98,7 @@ namespace Renci.SshNet
                                 cipherKey = keyData.Take(32);
                                 cipherIV = new byte[16];
 
-                                macKey = CryptoAbstraction.HashSHA1(Encoding.UTF8.GetBytes("putty-private-key-file-mac-key" + _passPhrase)).Take(20);
+                                macKey = SHA1.HashData(Encoding.UTF8.GetBytes("putty-private-key-file-mac-key" + _passPhrase)).Take(20);
                                 hmac = new HMACSHA1(macKey);
 
                                 break;
@@ -124,7 +119,7 @@ namespace Renci.SshNet
                                 hmac = new HMACSHA256(Array.Empty<byte>());
                                 break;
                             case "2":
-                                var macKey = CryptoAbstraction.HashSHA1(Encoding.UTF8.GetBytes("putty-private-key-file-mac-key"));
+                                var macKey = SHA1.HashData(Encoding.UTF8.GetBytes("putty-private-key-file-mac-key"));
                                 hmac = new HMACSHA1(macKey);
                                 break;
                             default:
@@ -153,21 +148,19 @@ namespace Renci.SshNet
                 {
                     macValue = hmac.ComputeHash(macData);
                 }
-#if NET
+
                 var reference = Convert.FromHexString(_mac);
-#else
-                var reference = Org.BouncyCastle.Utilities.Encoders.Hex.Decode(_mac);
-#endif
+
                 if (!macValue.SequenceEqual(reference))
                 {
                     throw new SshException("MAC verification failed for PuTTY key file");
                 }
 
-                var publicKeyReader = new SshDataStream(_publicKey);
+                using var publicKeyReader = new SshDataStream(_publicKey);
                 var keyType = publicKeyReader.ReadString(Encoding.UTF8);
                 Debug.Assert(keyType == _algorithmName, $"{nameof(keyType)} is not the same as {nameof(_algorithmName)}");
 
-                var privateKeyReader = new SshDataStream(privateKey);
+                using var privateKeyReader = new SshDataStream(privateKey);
 
                 Key parsedKey;
 

src/Renci.SshNet/PrivateKeyFile.SSHCOM.cs

@@ -28,22 +28,22 @@ namespace Renci.SshNet
 
             public Key Parse()
             {
-                var reader = new SshDataStream(_data);
-                var magicNumber = reader.ReadUInt32();
+                using var dataReader = new SshDataStream(_data);
+                var magicNumber = dataReader.ReadUInt32();
                 if (magicNumber != 0x3f6ff9eb)
                 {
                     throw new SshException("Invalid SSH2 private key.");
                 }
 
-                _ = reader.ReadUInt32(); // Read total bytes length including magic number
-                var keyType = reader.ReadString(SshData.Ascii);
-                var ssh2CipherName = reader.ReadString(SshData.Ascii);
-                var blobSize = (int)reader.ReadUInt32();
+                _ = dataReader.ReadUInt32(); // Read total bytes length including magic number
+                var keyType = dataReader.ReadString(SshData.Ascii);
+                var ssh2CipherName = dataReader.ReadString(SshData.Ascii);
+                var blobSize = (int)dataReader.ReadUInt32();
 
                 byte[] keyData;
                 if (ssh2CipherName == "none")
                 {
-                    keyData = reader.ReadBytes(blobSize);
+                    keyData = dataReader.ReadBytes(blobSize);
                 }
                 else if (ssh2CipherName == "3des-cbc")
                 {
@@ -53,17 +53,17 @@ namespace Renci.SshNet
                     }
 
                     var key = GetCipherKey(_passPhrase, 192 / 8);
-                    var ssh2Сipher = new TripleDesCipher(key, new byte[8], CipherMode.CBC, pkcs7Padding: false);
-                    keyData = ssh2Сipher.Decrypt(reader.ReadBytes(blobSize));
+                    using var ssh2Сipher = new TripleDesCipher(key, new byte[8], CipherMode.CBC, pkcs7Padding: false);
+                    keyData = ssh2Сipher.Decrypt(dataReader.ReadBytes(blobSize));
                 }
                 else
                 {
                     throw new SshException(string.Format("Cipher method '{0}' is not supported.", ssh2CipherName));
                 }
 
-                reader = new SshDataStream(keyData);
+                using var keyReader = new SshDataStream(keyData);
 
-                var decryptedLength = reader.ReadUInt32();
+                var decryptedLength = keyReader.ReadUInt32();
 
                 if (decryptedLength > blobSize - 4)
                 {
@@ -72,12 +72,12 @@ namespace Renci.SshNet
 
                 if (keyType.Contains("rsa"))
                 {
-                    var exponent = ReadBigIntWithBits(reader);
-                    var d = ReadBigIntWithBits(reader);
-                    var modulus = ReadBigIntWithBits(reader);
-                    var inverseQ = ReadBigIntWithBits(reader);
-                    var q = ReadBigIntWithBits(reader);
-                    var p = ReadBigIntWithBits(reader);
+                    var exponent = ReadBigIntWithBits(keyReader);
+                    var d = ReadBigIntWithBits(keyReader);
+                    var modulus = ReadBigIntWithBits(keyReader);
+                    var inverseQ = ReadBigIntWithBits(keyReader);
+                    var q = ReadBigIntWithBits(keyReader);
+                    var p = ReadBigIntWithBits(keyReader);
                     return new RsaKey(modulus, exponent, d, p, q, inverseQ);
                 }
 

src/Renci.SshNet/PrivateKeyFile.cs

@@ -172,7 +172,7 @@ namespace Renci.SshNet
         /// <param name="key">The key.</param>
         public PrivateKeyFile(Key key)
         {
-            ThrowHelper.ThrowIfNull(key);
+            ArgumentNullException.ThrowIfNull(key);
 
             _key = key;
             _hostAlgorithms.Add(new KeyHostAlgorithm(key.ToString(), key));
@@ -223,7 +223,7 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="fileName"/> is <see langword="null"/>.</exception>
         public PrivateKeyFile(string fileName, string? passPhrase, string? certificateFileName)
         {
-            ThrowHelper.ThrowIfNull(fileName);
+            ArgumentNullException.ThrowIfNull(fileName);
 
             using (var keyFile = File.OpenRead(fileName))
             {
@@ -263,7 +263,7 @@ namespace Renci.SshNet
         /// <param name="certificate">A certificate which certifies the private key.</param>
         public PrivateKeyFile(Stream privateKey, string? passPhrase, Stream? certificate)
         {
-            ThrowHelper.ThrowIfNull(privateKey);
+            ArgumentNullException.ThrowIfNull(privateKey);
 
             Open(privateKey, passPhrase);
 
@@ -370,10 +370,8 @@ namespace Renci.SshNet
             if (_key is RsaKey rsaKey)
             {
                 _hostAlgorithms.Add(new KeyHostAlgorithm("ssh-rsa", _key));
-#pragma warning disable CA2000 // Dispose objects before losing scope
                 _hostAlgorithms.Add(new KeyHostAlgorithm("rsa-sha2-512", _key, new RsaDigitalSignature(rsaKey, HashAlgorithmName.SHA512)));
                 _hostAlgorithms.Add(new KeyHostAlgorithm("rsa-sha2-256", _key, new RsaDigitalSignature(rsaKey, HashAlgorithmName.SHA256)));
-#pragma warning restore CA2000 // Dispose objects before losing scope
             }
             else
             {
@@ -420,7 +418,6 @@ namespace Renci.SshNet
 
                 _hostAlgorithms.Insert(0, new CertificateHostAlgorithm("ssh-rsa-cert-v01@openssh.com", Key, Certificate));
 
-#pragma warning disable CA2000 // Dispose objects before losing scope
                 _hostAlgorithms.Insert(0, new CertificateHostAlgorithm(
                     "rsa-sha2-256-cert-v01@openssh.com",
                     Key,
@@ -432,7 +429,6 @@ namespace Renci.SshNet
                     Key,
                     Certificate,
                     new RsaDigitalSignature(rsaKey, HashAlgorithmName.SHA512)));
-#pragma warning restore CA2000 // Dispose objects before losing scope
             }
             else
             {

src/Renci.SshNet/RemotePathDoubleQuoteTransformation.cs

@@ -1,8 +1,6 @@
 using System;
 using System.Text;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet
 {
     /// <summary>
@@ -52,7 +50,7 @@ namespace Renci.SshNet
         /// </example>
         public string Transform(string path)
         {
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             var transformed = new StringBuilder(path.Length);
 

src/Renci.SshNet/RemotePathNoneTransformation.cs

@@ -1,7 +1,5 @@
 using System;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet
 {
     /// <summary>
@@ -23,7 +21,7 @@ namespace Renci.SshNet
         /// </remarks>
         public string Transform(string path)
         {
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             return path;
         }

src/Renci.SshNet/RemotePathShellQuoteTransformation.cs

@@ -1,8 +1,6 @@
 using System;
 using System.Text;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet
 {
     /// <summary>
@@ -82,7 +80,7 @@ namespace Renci.SshNet
         /// </example>
         public string Transform(string path)
         {
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             // result is at least value and (likely) leading/trailing single-quotes
             var sb = new StringBuilder(path.Length + 2);

src/Renci.SshNet/Renci.SshNet.csproj

@@ -4,7 +4,7 @@
     <AssemblyName>Renci.SshNet</AssemblyName>
     <Product>SSH.NET</Product>
     <AssemblyTitle>SSH.NET</AssemblyTitle>
-    <TargetFrameworks>net462;netstandard2.0;net8.0;net9.0</TargetFrameworks>
+    <TargetFrameworks>net462;netstandard2.0;net8.0;net9.0;net10.0</TargetFrameworks>
   </PropertyGroup>
 
   <PropertyGroup>

src/Renci.SshNet/ScpClient.cs

@@ -2,7 +2,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.IO;
 using System.Net;
@@ -116,7 +115,7 @@ namespace Renci.SshNet
             }
             set
             {
-                ThrowHelper.ThrowIfNull(value);
+                ArgumentNullException.ThrowIfNull(value);
 
                 _remotePathTransformation = value;
             }
@@ -152,7 +151,6 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="password"/> is <see langword="null"/>.</exception>
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, or <paramref name="username"/> is <see langword="null"/> or contains only whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
-        [SuppressMessage("Microsoft.Reliability", "CA2000:DisposeObjectsBeforeLosingScope", Justification = "Disposed in Dispose(bool) method.")]
         public ScpClient(string host, int port, string username, string password)
             : this(new PasswordConnectionInfo(host, port, username, password), ownsConnectionInfo: true)
         {
@@ -181,7 +179,6 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="keyFiles"/> is <see langword="null"/>.</exception>
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, -or- <paramref name="username"/> is <see langword="null"/> or contains only whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
-        [SuppressMessage("Microsoft.Reliability", "CA2000:DisposeObjectsBeforeLosingScope", Justification = "Disposed in Dispose(bool) method.")]
         public ScpClient(string host, int port, string username, params IPrivateKeySource[] keyFiles)
             : this(new PrivateKeyConnectionInfo(host, port, username, keyFiles), ownsConnectionInfo: true)
         {
@@ -288,7 +285,7 @@ namespace Renci.SshNet
         /// <exception cref="SshConnectionException">Client is not connected.</exception>
         public void Upload(FileInfo fileInfo, string path)
         {
-            ThrowHelper.ThrowIfNull(fileInfo);
+            ArgumentNullException.ThrowIfNull(fileInfo);
 
             if (Session is null)
             {
@@ -335,8 +332,8 @@ namespace Renci.SshNet
         /// <exception cref="SshConnectionException">Client is not connected.</exception>
         public void Upload(DirectoryInfo directoryInfo, string path)
         {
-            ThrowHelper.ThrowIfNull(directoryInfo);
-            ThrowHelper.ThrowIfNullOrEmpty(path);
+            ArgumentNullException.ThrowIfNull(directoryInfo);
+            ArgumentException.ThrowIfNullOrEmpty(path);
 
             if (Session is null)
             {
@@ -378,8 +375,8 @@ namespace Renci.SshNet
         /// <exception cref="SshConnectionException">Client is not connected.</exception>
         public void Download(string filename, FileInfo fileInfo)
         {
-            ThrowHelper.ThrowIfNullOrEmpty(filename);
-            ThrowHelper.ThrowIfNull(fileInfo);
+            ArgumentException.ThrowIfNullOrEmpty(filename);
+            ArgumentNullException.ThrowIfNull(fileInfo);
 
             if (Session is null)
             {
@@ -418,8 +415,8 @@ namespace Renci.SshNet
         /// <exception cref="SshConnectionException">Client is not connected.</exception>
         public void Download(string directoryName, DirectoryInfo directoryInfo)
         {
-            ThrowHelper.ThrowIfNullOrEmpty(directoryName);
-            ThrowHelper.ThrowIfNull(directoryInfo);
+            ArgumentException.ThrowIfNullOrEmpty(directoryName);
+            ArgumentNullException.ThrowIfNull(directoryInfo);
 
             if (Session is null)
             {
@@ -458,8 +455,8 @@ namespace Renci.SshNet
         /// <exception cref="SshConnectionException">Client is not connected.</exception>
         public void Download(string filename, Stream destination)
         {
-            ThrowHelper.ThrowIfNullOrWhiteSpace(filename);
-            ThrowHelper.ThrowIfNull(destination);
+            ArgumentException.ThrowIfNullOrWhiteSpace(filename);
+            ArgumentNullException.ThrowIfNull(destination);
 
             if (Session is null)
             {
@@ -675,11 +672,7 @@ namespace Renci.SshNet
         /// <param name="fileOrDirectory">The file or directory to upload.</param>
         private void UploadTimes(IChannelSession channel, Stream input, FileSystemInfo fileOrDirectory)
         {
-#if NET
             var zeroTime = DateTime.UnixEpoch;
-#else
-            var zeroTime = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
-#endif
             var modificationSeconds = (long)(fileOrDirectory.LastWriteTimeUtc - zeroTime).TotalSeconds;
             var accessSeconds = (long)(fileOrDirectory.LastAccessTimeUtc - zeroTime).TotalSeconds;
             SendData(channel, string.Format(CultureInfo.InvariantCulture, "T{0} 0 {1} 0\n", modificationSeconds, accessSeconds));
@@ -856,11 +849,7 @@ namespace Renci.SshNet
                     var mtime = long.Parse(match.Result("${mtime}"), CultureInfo.InvariantCulture);
                     var atime = long.Parse(match.Result("${atime}"), CultureInfo.InvariantCulture);
 
-#if NET
                     var zeroTime = DateTime.UnixEpoch;
-#else
-                    var zeroTime = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
-#endif
                     modifiedTime = zeroTime.AddSeconds(mtime);
                     accessedTime = zeroTime.AddSeconds(atime);
                     continue;

src/Renci.SshNet/Security/Certificate.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Collections.Generic;
 using System.Numerics;
+using System.Security.Cryptography;
 
-using Renci.SshNet.Abstractions;
 using Renci.SshNet.Common;
 
 namespace Renci.SshNet.Security
@@ -228,7 +228,7 @@ namespace Renci.SshNet.Security
         {
             get
             {
-                return Convert.ToBase64String(CryptoAbstraction.HashSHA256(CertificateAuthorityKey)).TrimEnd('=');
+                return Convert.ToBase64String(SHA256.HashData(CertificateAuthorityKey)).TrimEnd('=');
             }
         }
 

src/Renci.SshNet/Security/Cryptography/Ciphers/AesCipher.BclImpl.cs

@@ -25,7 +25,7 @@ namespace Renci.SshNet.Security.Cryptography.Ciphers
 
                 if (cipherMode != System.Security.Cryptography.CipherMode.ECB)
                 {
-                    ThrowHelper.ThrowIfNull(iv);
+                    ArgumentNullException.ThrowIfNull(iv);
 
                     aes.IV = iv.Take(16);
                 }

src/Renci.SshNet/Security/Cryptography/ED25519DigitalSignature.cs

@@ -21,7 +21,7 @@ namespace Renci.SshNet.Security.Cryptography
         /// <exception cref="ArgumentNullException"><paramref name="key"/> is <see langword="null"/>.</exception>
         public ED25519DigitalSignature(ED25519Key key)
         {
-            ThrowHelper.ThrowIfNull(key);
+            ArgumentNullException.ThrowIfNull(key);
 
             _key = key;
         }

src/Renci.SshNet/Security/Cryptography/ED25519Key.cs

@@ -78,7 +78,7 @@ namespace Renci.SshNet.Security
         /// <param name="publicKeyData">The encoded public key data.</param>
         public ED25519Key(SshKeyData publicKeyData)
         {
-            ThrowHelper.ThrowIfNull(publicKeyData);
+            ArgumentNullException.ThrowIfNull(publicKeyData);
 
             if (publicKeyData.Name != "ssh-ed25519" || publicKeyData.Keys.Length != 1)
             {

src/Renci.SshNet/Security/Cryptography/EcdsaDigitalSignature.cs

@@ -18,7 +18,7 @@ namespace Renci.SshNet.Security.Cryptography
         /// <exception cref="ArgumentNullException"><paramref name="key"/> is <see langword="null"/>.</exception>
         public EcdsaDigitalSignature(EcdsaKey key)
         {
-            ThrowHelper.ThrowIfNull(key);
+            ArgumentNullException.ThrowIfNull(key);
 
             _key = key;
         }

src/Renci.SshNet/Security/Cryptography/EcdsaKey.cs

@@ -188,7 +188,7 @@ namespace Renci.SshNet.Security
         /// <param name="publicKeyData">The encoded public key data.</param>
         public EcdsaKey(SshKeyData publicKeyData)
         {
-            ThrowHelper.ThrowIfNull(publicKeyData);
+            ArgumentNullException.ThrowIfNull(publicKeyData);
 
             if (!publicKeyData.Name.StartsWith("ecdsa-sha2-", StringComparison.Ordinal) || publicKeyData.Keys.Length != 2)
             {

src/Renci.SshNet/Security/Cryptography/RsaKey.cs

@@ -139,7 +139,7 @@ namespace Renci.SshNet.Security
         /// <param name="publicKeyData">The encoded public key data.</param>
         public RsaKey(SshKeyData publicKeyData)
         {
-            ThrowHelper.ThrowIfNull(publicKeyData);
+            ArgumentNullException.ThrowIfNull(publicKeyData);
 
             if (publicKeyData.Name != "ssh-rsa" || publicKeyData.Keys.Length != 2)
             {
@@ -159,7 +159,7 @@ namespace Renci.SshNet.Security
         /// <param name="privateKeyData">DER encoded private key data.</param>
         public RsaKey(byte[] privateKeyData)
         {
-            ThrowHelper.ThrowIfNull(privateKeyData);
+            ArgumentNullException.ThrowIfNull(privateKeyData);
 
             var keyReader = new AsnReader(privateKeyData, AsnEncodingRules.DER);
             var sequenceReader = keyReader.ReadSequence();

src/Renci.SshNet/Security/Cryptography/SymmetricCipher.cs

@@ -1,7 +1,5 @@
 using System;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet.Security.Cryptography
 {
     /// <summary>
@@ -21,7 +19,7 @@ namespace Renci.SshNet.Security.Cryptography
         /// <exception cref="ArgumentNullException"><paramref name="key"/> is <see langword="null"/>.</exception>
         protected SymmetricCipher(byte[] key)
         {
-            ThrowHelper.ThrowIfNull(key);
+            ArgumentNullException.ThrowIfNull(key);
 
             Key = key;
         }

src/Renci.SshNet/Security/KeyExchange.cs

@@ -91,17 +91,17 @@ namespace Renci.SshNet.Security
             {
                 _logger.LogTrace("[{SessionId}] Host key algorithm: we offer {WeOffer}",
                     Session.SessionIdHex,
-                    session.ConnectionInfo.HostKeyAlgorithms.Keys.Join(","));
+                    string.Join(',', session.ConnectionInfo.HostKeyAlgorithms.Keys));
 
                 _logger.LogTrace("[{SessionId}] Host key algorithm: they offer {TheyOffer}",
                     Session.SessionIdHex,
-                    message.ServerHostKeyAlgorithms.Join(","));
+                    string.Join(',', message.ServerHostKeyAlgorithms));
             }
 
             if (hostKeyAlgorithmName is null)
             {
                 throw new SshConnectionException(
-                    $"No matching host key algorithm (server offers {message.ServerHostKeyAlgorithms.Join(",")})",
+                    $"No matching host key algorithm (server offers {string.Join(',', message.ServerHostKeyAlgorithms)})",
                     DisconnectReason.KeyExchangeFailed);
             }
 
@@ -118,17 +118,17 @@ namespace Renci.SshNet.Security
             {
                 _logger.LogTrace("[{SessionId}] Encryption client to server: we offer {WeOffer}",
                     Session.SessionIdHex,
-                    session.ConnectionInfo.Encryptions.Keys.Join(","));
+                    string.Join(',', session.ConnectionInfo.Encryptions.Keys));
 
                 _logger.LogTrace("[{SessionId}] Encryption client to server: they offer {TheyOffer}",
                     Session.SessionIdHex,
-                    message.EncryptionAlgorithmsClientToServer.Join(","));
+                    string.Join(',', message.EncryptionAlgorithmsClientToServer));
             }
 
             if (clientEncryptionAlgorithmName is null)
             {
                 throw new SshConnectionException(
-                    $"No matching client encryption algorithm (server offers {message.EncryptionAlgorithmsClientToServer.Join(",")})",
+                    $"No matching client encryption algorithm (server offers {string.Join(',', message.EncryptionAlgorithmsClientToServer)})",
                     DisconnectReason.KeyExchangeFailed);
             }
 
@@ -145,17 +145,17 @@ namespace Renci.SshNet.Security
             {
                 _logger.LogTrace("[{SessionId}] Encryption server to client: we offer {WeOffer}",
                     Session.SessionIdHex,
-                    session.ConnectionInfo.Encryptions.Keys.Join(","));
+                    string.Join(',', session.ConnectionInfo.Encryptions.Keys));
 
                 _logger.LogTrace("[{SessionId}] Encryption server to client: they offer {TheyOffer}",
                     Session.SessionIdHex,
-                    message.EncryptionAlgorithmsServerToClient.Join(","));
+                    string.Join(',', message.EncryptionAlgorithmsServerToClient));
             }
 
             if (serverDecryptionAlgorithmName is null)
             {
                 throw new SshConnectionException(
-                    $"No matching server encryption algorithm (server offers {message.EncryptionAlgorithmsServerToClient.Join(",")})",
+                    $"No matching server encryption algorithm (server offers {string.Join(',', message.EncryptionAlgorithmsServerToClient)})",
                     DisconnectReason.KeyExchangeFailed);
             }
 
@@ -174,17 +174,17 @@ namespace Renci.SshNet.Security
                 {
                     _logger.LogTrace("[{SessionId}] MAC client to server: we offer {WeOffer}",
                         Session.SessionIdHex,
-                        session.ConnectionInfo.HmacAlgorithms.Keys.Join(","));
+                        string.Join(',', session.ConnectionInfo.HmacAlgorithms.Keys));
 
                     _logger.LogTrace("[{SessionId}] MAC client to server: they offer {TheyOffer}",
                         Session.SessionIdHex,
-                        message.MacAlgorithmsClientToServer.Join(","));
+                        string.Join(',', message.MacAlgorithmsClientToServer));
                 }
 
                 if (clientHmacAlgorithmName is null)
                 {
                     throw new SshConnectionException(
-                        $"No matching client MAC algorithm (server offers {message.MacAlgorithmsClientToServer.Join(",")})",
+                        $"No matching client MAC algorithm (server offers {string.Join(',', message.MacAlgorithmsClientToServer)})",
                         DisconnectReason.KeyExchangeFailed);
                 }
 
@@ -204,17 +204,17 @@ namespace Renci.SshNet.Security
                 {
                     _logger.LogTrace("[{SessionId}] MAC server to client: we offer {WeOffer}",
                         Session.SessionIdHex,
-                        session.ConnectionInfo.HmacAlgorithms.Keys.Join(","));
+                        string.Join(',', session.ConnectionInfo.HmacAlgorithms.Keys));
 
                     _logger.LogTrace("[{SessionId}] MAC server to client: they offer {TheyOffer}",
                         Session.SessionIdHex,
-                        message.MacAlgorithmsServerToClient.Join(","));
+                        string.Join(',', message.MacAlgorithmsServerToClient));
                 }
 
                 if (serverHmacAlgorithmName is null)
                 {
                     throw new SshConnectionException(
-                        $"No matching server MAC algorithm (server offers {message.MacAlgorithmsServerToClient.Join(",")})",
+                        $"No matching server MAC algorithm (server offers {string.Join(',', message.MacAlgorithmsServerToClient)})",
                         DisconnectReason.KeyExchangeFailed);
                 }
 
@@ -232,17 +232,17 @@ namespace Renci.SshNet.Security
             {
                 _logger.LogTrace("[{SessionId}] Compression client to server: we offer {WeOffer}",
                     Session.SessionIdHex,
-                    session.ConnectionInfo.CompressionAlgorithms.Keys.Join(","));
+                    string.Join(',', session.ConnectionInfo.CompressionAlgorithms.Keys));
 
                 _logger.LogTrace("[{SessionId}] Compression client to server: they offer {TheyOffer}",
                     Session.SessionIdHex,
-                    message.CompressionAlgorithmsClientToServer.Join(","));
+                    string.Join(',', message.CompressionAlgorithmsClientToServer));
             }
 
             if (compressionAlgorithmName is null)
             {
                 throw new SshConnectionException(
-                    $"No matching client compression algorithm (server offers {message.CompressionAlgorithmsClientToServer.Join(",")})",
+                    $"No matching client compression algorithm (server offers {string.Join(',', message.CompressionAlgorithmsClientToServer)})",
                     DisconnectReason.KeyExchangeFailed);
             }
 
@@ -259,17 +259,17 @@ namespace Renci.SshNet.Security
             {
                 _logger.LogTrace("[{SessionId}] Compression server to client: we offer {WeOffer}",
                     Session.SessionIdHex,
-                    session.ConnectionInfo.CompressionAlgorithms.Keys.Join(","));
+                    string.Join(',', session.ConnectionInfo.CompressionAlgorithms.Keys));
 
                 _logger.LogTrace("[{SessionId}] Compression server to client: they offer {TheyOffer}",
                     Session.SessionIdHex,
-                    message.CompressionAlgorithmsServerToClient.Join(","));
+                    string.Join(',', message.CompressionAlgorithmsServerToClient));
             }
 
             if (decompressionAlgorithmName is null)
             {
                 throw new SshConnectionException(
-                    $"No matching server compression algorithm (server offers {message.CompressionAlgorithmsServerToClient.Join(",")})",
+                    $"No matching server compression algorithm (server offers {string.Join(',', message.CompressionAlgorithmsServerToClient)})",
                     DisconnectReason.KeyExchangeFailed);
             }
 

src/Renci.SshNet/Security/KeyExchangeDiffieHellman.cs

@@ -7,7 +7,6 @@ using Org.BouncyCastle.Crypto.Generators;
 using Org.BouncyCastle.Crypto.Parameters;
 
 using Renci.SshNet.Abstractions;
-using Renci.SshNet.Common;
 using Renci.SshNet.Messages.Transport;
 
 namespace Renci.SshNet.Security
@@ -53,9 +52,9 @@ namespace Renci.SshNet.Security
             DHParameters parameters,
             HashAlgorithmName hashAlgorithm)
         {
-            ThrowHelper.ThrowIfNull(name);
-            ThrowHelper.ThrowIfNull(parameters);
-            ThrowHelper.ThrowIfNullOrEmpty(hashAlgorithm.Name, nameof(hashAlgorithm));
+            ArgumentNullException.ThrowIfNull(name);
+            ArgumentNullException.ThrowIfNull(parameters);
+            ArgumentException.ThrowIfNullOrEmpty(hashAlgorithm.Name, nameof(hashAlgorithm));
 
             Name = name;
             _dhParameters = parameters;

src/Renci.SshNet/Security/KeyExchangeDiffieHellmanGroupExchange.cs

@@ -7,7 +7,6 @@ using Org.BouncyCastle.Crypto.Generators;
 using Org.BouncyCastle.Crypto.Parameters;
 
 using Renci.SshNet.Abstractions;
-using Renci.SshNet.Common;
 using Renci.SshNet.Messages.Transport;
 
 namespace Renci.SshNet.Security
@@ -83,8 +82,8 @@ namespace Renci.SshNet.Security
             uint preferredGroupSize,
             uint maximumGroupSize)
         {
-            ThrowHelper.ThrowIfNull(name);
-            ThrowHelper.ThrowIfNullOrEmpty(hashAlgorithm.Name, nameof(hashAlgorithm));
+            ArgumentNullException.ThrowIfNull(name);
+            ArgumentException.ThrowIfNullOrEmpty(hashAlgorithm.Name, nameof(hashAlgorithm));
 
             if (preferredGroupSize < minimumGroupSize || preferredGroupSize > maximumGroupSize)
             {

src/Renci.SshNet/Security/KeyExchangeECCurve25519.cs

@@ -1,4 +1,5 @@
-using Renci.SshNet.Abstractions;
+using System.Security.Cryptography;
+
 using Renci.SshNet.Common;
 using Renci.SshNet.Messages.Transport;
 
@@ -89,7 +90,7 @@ namespace Renci.SshNet.Security
         /// </returns>
         protected override byte[] Hash(byte[] hashData)
         {
-            return CryptoAbstraction.HashSHA256(hashData);
+            return SHA256.HashData(hashData);
         }
 
         private void Session_KeyExchangeEcdhReplyMessageReceived(object sender, MessageEventArgs<KeyExchangeEcdhReplyMessage> e)

src/Renci.SshNet/Security/KeyExchangeECDH256.cs

@@ -1,7 +1,7 @@
-using Org.BouncyCastle.Asn1.Sec;
-using Org.BouncyCastle.Asn1.X9;
+using System.Security.Cryptography;
 
-using Renci.SshNet.Abstractions;
+using Org.BouncyCastle.Asn1.Sec;
+using Org.BouncyCastle.Asn1.X9;
 
 namespace Renci.SshNet.Security
 {
@@ -59,7 +59,7 @@ namespace Renci.SshNet.Security
         /// </returns>
         protected override byte[] Hash(byte[] hashData)
         {
-            return CryptoAbstraction.HashSHA256(hashData);
+            return SHA256.HashData(hashData);
         }
     }
 }

src/Renci.SshNet/Security/KeyExchangeECDH384.cs

@@ -1,7 +1,7 @@
-using Org.BouncyCastle.Asn1.Sec;
-using Org.BouncyCastle.Asn1.X9;
+using System.Security.Cryptography;
 
-using Renci.SshNet.Abstractions;
+using Org.BouncyCastle.Asn1.Sec;
+using Org.BouncyCastle.Asn1.X9;
 
 namespace Renci.SshNet.Security
 {
@@ -59,7 +59,7 @@ namespace Renci.SshNet.Security
         /// </returns>
         protected override byte[] Hash(byte[] hashData)
         {
-            return CryptoAbstraction.HashSHA384(hashData);
+            return SHA384.HashData(hashData);
         }
     }
 }

src/Renci.SshNet/Security/KeyExchangeECDH521.cs

@@ -1,7 +1,7 @@
-using Org.BouncyCastle.Asn1.Sec;
-using Org.BouncyCastle.Asn1.X9;
+using System.Security.Cryptography;
 
-using Renci.SshNet.Abstractions;
+using Org.BouncyCastle.Asn1.Sec;
+using Org.BouncyCastle.Asn1.X9;
 
 namespace Renci.SshNet.Security
 {
@@ -59,7 +59,7 @@ namespace Renci.SshNet.Security
         /// </returns>
         protected override byte[] Hash(byte[] hashData)
         {
-            return CryptoAbstraction.HashSHA512(hashData);
+            return SHA512.HashData(hashData);
         }
     }
 }

src/Renci.SshNet/Security/KeyExchangeMLKem768X25519Sha256.cs

@@ -1,5 +1,6 @@
 using System.Globalization;
 using System.Linq;
+using System.Security.Cryptography;
 
 using Org.BouncyCastle.Crypto.Generators;
 using Org.BouncyCastle.Crypto.Kems;
@@ -72,7 +73,7 @@ namespace Renci.SshNet.Security
         /// </returns>
         protected override byte[] Hash(byte[] hashData)
         {
-            return CryptoAbstraction.HashSHA256(hashData);
+            return SHA256.HashData(hashData);
         }
 
         private void Session_KeyExchangeHybridReplyMessageReceived(object sender, MessageEventArgs<KeyExchangeHybridReplyMessage> e)
@@ -113,7 +114,7 @@ namespace Renci.SshNet.Security
 
             var x25519Agreement = _impl.CalculateAgreement(serverExchangeValue.Take(_mlkemDecapsulator.EncapsulationLength, X25519PublicKeyParameters.KeySize));
 
-            SharedKey = CryptoAbstraction.HashSHA256(mlkemSecret.Concat(x25519Agreement));
+            SharedKey = SHA256.HashData(mlkemSecret.Concat(x25519Agreement));
         }
     }
 }

src/Renci.SshNet/Security/KeyExchangeSNtruP761X25519Sha512.cs

@@ -1,5 +1,6 @@
 using System.Globalization;
 using System.Linq;
+using System.Security.Cryptography;
 
 using Org.BouncyCastle.Crypto.Parameters;
 using Org.BouncyCastle.Pqc.Crypto.NtruPrime;
@@ -70,7 +71,7 @@ namespace Renci.SshNet.Security
         /// </returns>
         protected override byte[] Hash(byte[] hashData)
         {
-            return CryptoAbstraction.HashSHA512(hashData);
+            return SHA512.HashData(hashData);
         }
 
         private void Session_KeyExchangeEcdhReplyMessageReceived(object sender, MessageEventArgs<KeyExchangeEcdhReplyMessage> e)
@@ -111,7 +112,7 @@ namespace Renci.SshNet.Security
 
             var x25519Agreement = _impl.CalculateAgreement(serverExchangeValue.Take(_sntrup761Extractor.EncapsulationLength, X25519PublicKeyParameters.KeySize));
 
-            SharedKey = CryptoAbstraction.HashSHA512(sntrup761Secret.Concat(x25519Agreement));
+            SharedKey = SHA512.HashData(sntrup761Secret.Concat(x25519Agreement));
         }
     }
 }

src/Renci.SshNet/ServiceFactory.cs

@@ -85,8 +85,8 @@ namespace Renci.SshNet
         /// <inheritdoc/>
         public IKeyExchange CreateKeyExchange(IDictionary<string, Func<IKeyExchange>> clientAlgorithms, string[] serverAlgorithms)
         {
-            ThrowHelper.ThrowIfNull(clientAlgorithms);
-            ThrowHelper.ThrowIfNull(serverAlgorithms);
+            ArgumentNullException.ThrowIfNull(clientAlgorithms);
+            ArgumentNullException.ThrowIfNull(serverAlgorithms);
 
             // find an algorithm that is supported by both client and server
             var keyExchangeAlgorithmFactory = (from c in clientAlgorithms
@@ -96,7 +96,7 @@ namespace Renci.SshNet
 
             if (keyExchangeAlgorithmFactory is null)
             {
-                throw new SshConnectionException($"No matching key exchange algorithm (server offers {serverAlgorithms.Join(",")})", DisconnectReason.KeyExchangeFailed);
+                throw new SshConnectionException($"No matching key exchange algorithm (server offers {string.Join(',', serverAlgorithms)})", DisconnectReason.KeyExchangeFailed);
             }
 
             return keyExchangeAlgorithmFactory();
@@ -168,8 +168,8 @@ namespace Renci.SshNet
         /// <exception cref="NotSupportedException">The <see cref="IConnectionInfo.ProxyType"/> value of <paramref name="connectionInfo"/> is not supported.</exception>
         public IConnector CreateConnector(IConnectionInfo connectionInfo, ISocketFactory socketFactory)
         {
-            ThrowHelper.ThrowIfNull(connectionInfo);
-            ThrowHelper.ThrowIfNull(socketFactory);
+            ArgumentNullException.ThrowIfNull(connectionInfo);
+            ArgumentNullException.ThrowIfNull(socketFactory);
 
             var loggerFactory = connectionInfo.LoggerFactory ?? SshNetLoggingConfiguration.LoggerFactory;
 

src/Renci.SshNet/Session.cs

@@ -5,9 +5,6 @@ using System.Globalization;
 using System.Linq;
 using System.Net.Sockets;
 using System.Security.Cryptography;
-#if !NET
-using System.Text;
-#endif
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -298,7 +295,7 @@ namespace Renci.SshNet
             private set
             {
                 _sessionId = value;
-                SessionIdHex = ToHex(value);
+                SessionIdHex = value == null ? null : Convert.ToHexString(value);
             }
         }
 
@@ -545,9 +542,9 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="socketFactory"/> is <see langword="null"/>.</exception>
         internal Session(ConnectionInfo connectionInfo, IServiceFactory serviceFactory, ISocketFactory socketFactory)
         {
-            ThrowHelper.ThrowIfNull(connectionInfo);
-            ThrowHelper.ThrowIfNull(serviceFactory);
-            ThrowHelper.ThrowIfNull(socketFactory);
+            ArgumentNullException.ThrowIfNull(connectionInfo);
+            ArgumentNullException.ThrowIfNull(serviceFactory);
+            ArgumentNullException.ThrowIfNull(socketFactory);
 
             ConnectionInfo = connectionInfo;
             SessionLoggerFactory = connectionInfo.LoggerFactory ?? SshNetLoggingConfiguration.LoggerFactory;
@@ -925,7 +922,7 @@ namespace Renci.SshNet
         /// </returns>
         private WaitResult TryWait(WaitHandle waitHandle, TimeSpan timeout, out Exception exception)
         {
-            ThrowHelper.ThrowIfNull(waitHandle);
+            ArgumentNullException.ThrowIfNull(waitHandle);
 
             var waitHandles = new[]
                 {
@@ -987,7 +984,7 @@ namespace Renci.SshNet
         /// <exception cref="SocketException">A socket error was signaled while receiving messages from the server.</exception>
         internal void WaitOnHandle(WaitHandle waitHandle, TimeSpan timeout)
         {
-            ThrowHelper.ThrowIfNull(waitHandle);
+            ArgumentNullException.ThrowIfNull(waitHandle);
 
             var waitHandles = new[]
                 {
@@ -1546,17 +1543,11 @@ namespace Renci.SshNet
                 disposableClientCipher.Dispose();
             }
 
-            if (_serverMac != null)
-            {
-                _serverMac.Dispose();
-                _serverMac = null;
-            }
+            _serverMac?.Dispose();
+            _serverMac = null;
 
-            if (_clientMac != null)
-            {
-                _clientMac.Dispose();
-                _clientMac = null;
-            }
+            _clientMac?.Dispose();
+            _clientMac = null;
 
             // Update negotiated algorithms
             _serverCipher = _keyExchange.CreateServerCipher(out _serverAead);
@@ -1574,7 +1565,7 @@ namespace Renci.SshNet
             {
                 System.IO.File.AppendAllText(
                     path,
-                    $"{ToHex(ClientInitMessage.Cookie)} SHARED_SECRET {ToHex(kex.SharedKey)}{Environment.NewLine}");
+                    $"{Convert.ToHexString(ClientInitMessage.Cookie)} SHARED_SECRET {Convert.ToHexString(kex.SharedKey)}{Environment.NewLine}");
             }
 #endif
 
@@ -1843,27 +1834,6 @@ namespace Renci.SshNet
             return message;
         }
 
-        private static string ToHex(byte[] bytes)
-        {
-            if (bytes is null)
-            {
-                return null;
-            }
-
-#if NET
-            return Convert.ToHexString(bytes);
-#else
-            var builder = new StringBuilder(bytes.Length * 2);
-
-            foreach (var b in bytes)
-            {
-                builder.Append(b.ToString("X2"));
-            }
-
-            return builder.ToString();
-#endif
-        }
-
         /// <summary>
         /// Performs a blocking read on the socket until <paramref name="length"/> bytes are received.
         /// </summary>

src/Renci.SshNet/Sftp/Requests/SftpRealPathRequest.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Text;
 
-using Renci.SshNet.Common;
 using Renci.SshNet.Sftp.Responses;
 
 namespace Renci.SshNet.Sftp.Requests
@@ -44,7 +43,7 @@ namespace Renci.SshNet.Sftp.Requests
         public SftpRealPathRequest(uint protocolVersion, uint requestId, string path, Encoding encoding, Action<SftpNameResponse> nameAction, Action<SftpStatusResponse> statusAction)
             : base(protocolVersion, requestId, statusAction)
         {
-            ThrowHelper.ThrowIfNull(nameAction);
+            ArgumentNullException.ThrowIfNull(nameAction);
 
             Encoding = encoding;
             Path = path;

src/Renci.SshNet/Sftp/SftpFile.cs

@@ -33,8 +33,8 @@ namespace Renci.SshNet.Sftp
                 throw new SshConnectionException("Client not connected.");
             }
 
-            ThrowHelper.ThrowIfNull(attributes);
-            ThrowHelper.ThrowIfNull(fullName);
+            ArgumentNullException.ThrowIfNull(attributes);
+            ArgumentNullException.ThrowIfNull(fullName);
 
             _sftpSession = sftpSession;
             Attributes = attributes;
@@ -485,7 +485,7 @@ namespace Renci.SshNet.Sftp
         /// <exception cref="ArgumentNullException"><paramref name="destFileName"/> is <see langword="null"/>.</exception>
         public void MoveTo(string destFileName)
         {
-            ThrowHelper.ThrowIfNull(destFileName);
+            ArgumentNullException.ThrowIfNull(destFileName);
 
             _sftpSession.RequestRename(FullName, destFileName);
 

src/Renci.SshNet/Sftp/SftpFileStream.cs

@@ -191,7 +191,7 @@ namespace Renci.SshNet.Sftp
         {
             Debug.Assert(isAsync || cancellationToken == default);
 
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (bufferSize <= 0)
             {
@@ -332,7 +332,7 @@ namespace Renci.SshNet.Sftp
         /// <inheritdoc/>
         public override void Flush()
         {
-            ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+            ObjectDisposedException.ThrowIf(_disposed, this);
 
             var writeLength = _writeBuffer.ActiveLength;
 
@@ -363,7 +363,7 @@ namespace Renci.SshNet.Sftp
         /// <inheritdoc/>
         public override async Task FlushAsync(CancellationToken cancellationToken)
         {
-            ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+            ObjectDisposedException.ThrowIf(_disposed, this);
 
             var writeLength = _writeBuffer.ActiveLength;
 
@@ -662,7 +662,7 @@ namespace Renci.SshNet.Sftp
         /// <inheritdoc/>
         public override void SetLength(long value)
         {
-            ThrowHelper.ThrowIfNegative(value);
+            ArgumentOutOfRangeException.ThrowIfNegative(value);
             ThrowIfNotWriteable();
             ThrowIfNotSeekable();
 
@@ -755,7 +755,7 @@ namespace Renci.SshNet.Sftp
         {
             if (!CanSeek)
             {
-                ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+                ObjectDisposedException.ThrowIf(_disposed, this);
                 Throw();
             }
 
@@ -769,7 +769,7 @@ namespace Renci.SshNet.Sftp
         {
             if (!CanWrite)
             {
-                ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+                ObjectDisposedException.ThrowIf(_disposed, this);
                 Throw();
             }
 
@@ -783,7 +783,7 @@ namespace Renci.SshNet.Sftp
         {
             if (!CanRead)
             {
-                ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+                ObjectDisposedException.ThrowIf(_disposed, this);
                 Throw();
             }
 

src/Renci.SshNet/Sftp/SftpSession.cs

@@ -113,22 +113,14 @@ namespace Renci.SshNet.Sftp
             if (fullPath.EndsWith("/.", StringComparison.OrdinalIgnoreCase) ||
                 fullPath.EndsWith("/..", StringComparison.OrdinalIgnoreCase) ||
                 fullPath.Equals("/", StringComparison.OrdinalIgnoreCase) ||
-#if NET
                 fullPath.IndexOf('/', StringComparison.OrdinalIgnoreCase) < 0)
-#else
-                fullPath.IndexOf('/') < 0)
-#endif
             {
                 return fullPath;
             }
 
             var pathParts = fullPath.Split('/');
 
-#if NET
             var partialFullPath = string.Join('/', pathParts, 0, pathParts.Length - 1);
-#else
-            var partialFullPath = string.Join("/", pathParts, 0, pathParts.Length - 1);
-#endif
 
             if (string.IsNullOrEmpty(partialFullPath))
             {

src/Renci.SshNet/SftpClient.cs

@@ -3,7 +3,6 @@ using System;
 using System.Buffers;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.IO;
 using System.Linq;
@@ -202,7 +201,6 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="password"/> is <see langword="null"/>.</exception>
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid. <para>-or-</para> <paramref name="username"/> is <see langword="null"/> or contains only whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
-        [SuppressMessage("Microsoft.Reliability", "CA2000:DisposeObjectsBeforeLosingScope", Justification = "Disposed in Dispose(bool) method.")]
         public SftpClient(string host, int port, string username, string password)
             : this(new PasswordConnectionInfo(host, port, username, password), ownsConnectionInfo: true)
         {
@@ -231,7 +229,6 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="keyFiles"/> is <see langword="null"/>.</exception>
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid. <para>-or-</para> <paramref name="username"/> is <see langword="null"/> or contains only whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
-        [SuppressMessage("Microsoft.Reliability", "CA2000:DisposeObjectsBeforeLosingScope", Justification = "Disposed in Dispose(bool) method.")]
         public SftpClient(string host, int port, string username, params IPrivateKeySource[] keyFiles)
             : this(new PrivateKeyConnectionInfo(host, port, username, keyFiles), ownsConnectionInfo: true)
         {
@@ -299,7 +296,7 @@ namespace Renci.SshNet
         public void ChangeDirectory(string path)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (_sftpSession is null)
             {
@@ -324,7 +321,7 @@ namespace Renci.SshNet
         public Task ChangeDirectoryAsync(string path, CancellationToken cancellationToken = default)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (_sftpSession is null)
             {
@@ -365,7 +362,7 @@ namespace Renci.SshNet
         public void CreateDirectory(string path)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
 
             if (_sftpSession is null)
             {
@@ -391,7 +388,7 @@ namespace Renci.SshNet
         public async Task CreateDirectoryAsync(string path, CancellationToken cancellationToken = default)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
 
             if (_sftpSession is null)
             {
@@ -416,7 +413,7 @@ namespace Renci.SshNet
         public void DeleteDirectory(string path)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
 
             if (_sftpSession is null)
             {
@@ -432,7 +429,7 @@ namespace Renci.SshNet
         public async Task DeleteDirectoryAsync(string path, CancellationToken cancellationToken = default)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
 
             if (_sftpSession is null)
             {
@@ -459,7 +456,7 @@ namespace Renci.SshNet
         public void DeleteFile(string path)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
 
             if (_sftpSession is null)
             {
@@ -475,7 +472,7 @@ namespace Renci.SshNet
         public async Task DeleteFileAsync(string path, CancellationToken cancellationToken)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
 
             if (_sftpSession is null)
             {
@@ -517,8 +514,8 @@ namespace Renci.SshNet
         public void RenameFile(string oldPath, string newPath, bool isPosix)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(oldPath);
-            ThrowHelper.ThrowIfNull(newPath);
+            ArgumentNullException.ThrowIfNull(oldPath);
+            ArgumentNullException.ThrowIfNull(newPath);
 
             if (_sftpSession is null)
             {
@@ -554,8 +551,8 @@ namespace Renci.SshNet
         public async Task RenameFileAsync(string oldPath, string newPath, CancellationToken cancellationToken)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(oldPath);
-            ThrowHelper.ThrowIfNull(newPath);
+            ArgumentNullException.ThrowIfNull(oldPath);
+            ArgumentNullException.ThrowIfNull(newPath);
 
             if (_sftpSession is null)
             {
@@ -582,8 +579,8 @@ namespace Renci.SshNet
         public void SymbolicLink(string path, string linkPath)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
-            ThrowHelper.ThrowIfNullOrWhiteSpace(linkPath);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(linkPath);
 
             if (_sftpSession is null)
             {
@@ -634,7 +631,7 @@ namespace Renci.SshNet
         public async IAsyncEnumerable<ISftpFile> ListDirectoryAsync(string path, [EnumeratorCancellation] CancellationToken cancellationToken)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (_sftpSession is null)
             {
@@ -739,7 +736,7 @@ namespace Renci.SshNet
         public ISftpFile Get(string path)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (_sftpSession is null)
             {
@@ -769,7 +766,7 @@ namespace Renci.SshNet
         public async Task<ISftpFile> GetAsync(string path, CancellationToken cancellationToken)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (_sftpSession is null)
             {
@@ -800,7 +797,7 @@ namespace Renci.SshNet
         public bool Exists(string path)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
 
             if (_sftpSession is null)
             {
@@ -856,7 +853,7 @@ namespace Renci.SshNet
         public async Task<bool> ExistsAsync(string path, CancellationToken cancellationToken = default)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
 
             if (_sftpSession is null)
             {
@@ -900,8 +897,8 @@ namespace Renci.SshNet
         /// <inheritdoc />
         public void DownloadFile(string path, Stream output, Action<ulong>? downloadCallback = null)
         {
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
-            ThrowHelper.ThrowIfNull(output);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
+            ArgumentNullException.ThrowIfNull(output);
             CheckDisposed();
 
             InternalDownloadFile(
@@ -916,8 +913,8 @@ namespace Renci.SshNet
         /// <inheritdoc />
         public Task DownloadFileAsync(string path, Stream output, CancellationToken cancellationToken = default)
         {
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
-            ThrowHelper.ThrowIfNull(output);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
+            ArgumentNullException.ThrowIfNull(output);
             CheckDisposed();
 
             return InternalDownloadFile(
@@ -993,8 +990,8 @@ namespace Renci.SshNet
         /// </remarks>
         public IAsyncResult BeginDownloadFile(string path, Stream output, AsyncCallback? asyncCallback, object? state, Action<ulong>? downloadCallback = null)
         {
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
-            ThrowHelper.ThrowIfNull(output);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
+            ArgumentNullException.ThrowIfNull(output);
             CheckDisposed();
 
             var asyncResult = new SftpDownloadAsyncResult(asyncCallback, state);
@@ -1053,8 +1050,8 @@ namespace Renci.SshNet
         /// <inheritdoc/>
         public void UploadFile(Stream input, string path, bool canOverride, Action<ulong>? uploadCallback = null)
         {
-            ThrowHelper.ThrowIfNull(input);
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentNullException.ThrowIfNull(input);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
             CheckDisposed();
 
             var flags = Flags.Write | Flags.Truncate;
@@ -1081,8 +1078,8 @@ namespace Renci.SshNet
         /// <inheritdoc />
         public Task UploadFileAsync(Stream input, string path, CancellationToken cancellationToken = default)
         {
-            ThrowHelper.ThrowIfNull(input);
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentNullException.ThrowIfNull(input);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
             CheckDisposed();
 
             return InternalUploadFile(
@@ -1207,8 +1204,8 @@ namespace Renci.SshNet
         /// </remarks>
         public IAsyncResult BeginUploadFile(Stream input, string path, bool canOverride, AsyncCallback? asyncCallback, object? state, Action<ulong>? uploadCallback = null)
         {
-            ThrowHelper.ThrowIfNull(input);
-            ThrowHelper.ThrowIfNullOrWhiteSpace(path);
+            ArgumentNullException.ThrowIfNull(input);
+            ArgumentException.ThrowIfNullOrWhiteSpace(path);
             CheckDisposed();
 
             var flags = Flags.Write | Flags.Truncate;
@@ -1283,7 +1280,7 @@ namespace Renci.SshNet
         public SftpFileSystemInformation GetStatus(string path)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (_sftpSession is null)
             {
@@ -1310,7 +1307,7 @@ namespace Renci.SshNet
         public async Task<SftpFileSystemInformation> GetStatusAsync(string path, CancellationToken cancellationToken)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (_sftpSession is null)
             {
@@ -1340,7 +1337,7 @@ namespace Renci.SshNet
         public void AppendAllLines(string path, IEnumerable<string> contents)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(contents);
+            ArgumentNullException.ThrowIfNull(contents);
 
             using (var stream = AppendText(path))
             {
@@ -1364,7 +1361,7 @@ namespace Renci.SshNet
         public void AppendAllLines(string path, IEnumerable<string> contents, Encoding encoding)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(contents);
+            ArgumentNullException.ThrowIfNull(contents);
 
             using (var stream = AppendText(path, encoding))
             {
@@ -1447,7 +1444,7 @@ namespace Renci.SshNet
         public StreamWriter AppendText(string path, Encoding encoding)
         {
             CheckDisposed();
-            ThrowHelper.ThrowIfNull(encoding);
+            ArgumentNullException.ThrowIfNull(encoding);
 
             return new StreamWriter(Open(path, FileMode.Append, FileAccess.Write), encoding);
         }
@@ -1832,7 +1829,7 @@ namespace Renci.SshNet
         public IEnumerable<string> ReadLines(string path, Encoding encoding)
         {
             // We allow this usage exception to throw eagerly...
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             // ... but other exceptions will throw lazily i.e. inside the state machine created
             // by yield. We could choose to open the file eagerly as well in order to throw
@@ -1905,7 +1902,7 @@ namespace Renci.SshNet
         /// <inheritdoc/>
         public void WriteAllBytes(string path, byte[] bytes)
         {
-            ThrowHelper.ThrowIfNull(bytes);
+            ArgumentNullException.ThrowIfNull(bytes);
 
             UploadFile(new MemoryStream(bytes), path);
         }
@@ -2051,8 +2048,8 @@ namespace Renci.SshNet
         /// <exception cref="SshException">If a problem occurs while copying the file.</exception>
         public IEnumerable<FileInfo> SynchronizeDirectories(string sourcePath, string destinationPath, string searchPattern)
         {
-            ThrowHelper.ThrowIfNull(sourcePath);
-            ThrowHelper.ThrowIfNullOrWhiteSpace(destinationPath);
+            ArgumentNullException.ThrowIfNull(sourcePath);
+            ArgumentException.ThrowIfNullOrWhiteSpace(destinationPath);
 
             return InternalSynchronizeDirectories(sourcePath, destinationPath, searchPattern, asyncResult: null);
         }
@@ -2073,9 +2070,9 @@ namespace Renci.SshNet
         /// <exception cref="SshException">If a problem occurs while copying the file.</exception>
         public IAsyncResult BeginSynchronizeDirectories(string sourcePath, string destinationPath, string searchPattern, AsyncCallback? asyncCallback, object? state)
         {
-            ThrowHelper.ThrowIfNull(sourcePath);
-            ThrowHelper.ThrowIfNullOrWhiteSpace(destinationPath);
-            ThrowHelper.ThrowIfNull(searchPattern);
+            ArgumentNullException.ThrowIfNull(sourcePath);
+            ArgumentException.ThrowIfNullOrWhiteSpace(destinationPath);
+            ArgumentNullException.ThrowIfNull(searchPattern);
 
             var asyncResult = new SftpSynchronizeDirectoriesAsyncResult(asyncCallback, state);
 
@@ -2175,6 +2172,7 @@ namespace Renci.SshNet
                         {
                             using (var file = File.OpenRead(localFile.FullName))
                             {
+#pragma warning disable CA2025 // Do not pass 'IDisposable' instances into unawaited tasks
                                 InternalUploadFile(
                                     file,
                                     remoteFileName,
@@ -2183,6 +2181,7 @@ namespace Renci.SshNet
                                     uploadCallback: null,
                                     isAsync: false,
                                     CancellationToken.None).GetAwaiter().GetResult();
+#pragma warning restore CA2025 // Do not pass 'IDisposable' instances into unawaited tasks
                             }
 
                             uploadedFiles.Add(localFile);
@@ -2218,7 +2217,7 @@ namespace Renci.SshNet
         /// <exception cref="SshConnectionException">Client not connected.</exception>
         private List<ISftpFile> InternalListDirectory(string path, SftpListDirectoryAsyncResult? asyncResult, Action<int>? listCallback)
         {
-            ThrowHelper.ThrowIfNull(path);
+            ArgumentNullException.ThrowIfNull(path);
 
             if (_sftpSession is null)
             {
@@ -2270,7 +2269,7 @@ namespace Renci.SshNet
             return result;
         }
 
-#pragma warning disable S6966 // Awaitable method should be used
+#pragma warning disable CA1849 // Call async methods when in an async method
         private async Task InternalDownloadFile(
             string path,
             Stream output,
@@ -2385,9 +2384,7 @@ namespace Renci.SshNet
                 }
             }
         }
-#pragma warning restore S6966 // Awaitable method should be used
 
-#pragma warning disable S6966 // Awaitable method should be used
         private async Task InternalUploadFile(
             Stream input,
             string path,
@@ -2526,7 +2523,7 @@ namespace Renci.SshNet
                 _sftpSession.RequestClose(handle);
             }
         }
-#pragma warning restore S6966 // Awaitable method should be used
+#pragma warning restore CA1849 // Call async methods when in an async method
 
         /// <summary>
         /// Called when client is connected to the server.

src/Renci.SshNet/ShellStream.cs

@@ -215,7 +215,7 @@ namespace Renci.SshNet
         /// <inheritdoc/>
         public override void Flush()
         {
-            ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+            ObjectDisposedException.ThrowIf(_disposed, this);
 
             if (_writeBuffer.ActiveLength > 0)
             {
@@ -295,7 +295,7 @@ namespace Renci.SshNet
         /// <exception cref="ObjectDisposedException">The stream is closed.</exception>
         public void ChangeWindowSize(uint columns, uint rows, uint width, uint height)
         {
-            ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+            ObjectDisposedException.ThrowIf(_disposed, this);
 
             _channel.SendWindowChangeRequest(columns, rows, width, height);
         }
@@ -864,7 +864,7 @@ namespace Renci.SshNet
         private void Write(ReadOnlySpan<byte> buffer)
 #endif
         {
-            ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+            ObjectDisposedException.ThrowIf(_disposed, this);
 
             while (!buffer.IsEmpty)
             {
@@ -909,7 +909,7 @@ namespace Renci.SshNet
         private async ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken)
 #endif
         {
-            ThrowHelper.ThrowObjectDisposedIf(_disposed, this);
+            ObjectDisposedException.ThrowIf(_disposed, this);
 
             while (!buffer.IsEmpty)
             {

src/Renci.SshNet/SshClient.cs

@@ -1,7 +1,6 @@
 #nullable enable
 using System;
 using System.Collections.Generic;
-using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Net;
 using System.Text;
@@ -58,9 +57,7 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, or <paramref name="username"/> is <see langword="null"/> or contains only whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
         public SshClient(string host, int port, string username, string password)
-#pragma warning disable CA2000 // Dispose objects before losing scope
             : this(new PasswordConnectionInfo(host, port, username, password), ownsConnectionInfo: true)
-#pragma warning restore CA2000 // Dispose objects before losing scope
         {
         }
 
@@ -87,7 +84,6 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="keyFiles"/> is <see langword="null"/>.</exception>
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, -or- <paramref name="username"/> is <see langword="null"/> or contains only whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
-        [SuppressMessage("Microsoft.Reliability", "CA2000:DisposeObjectsBeforeLosingScope", Justification = "Disposed in Dispose(bool) method.")]
         public SshClient(string host, int port, string username, params IPrivateKeySource[] keyFiles)
             : this(new PrivateKeyConnectionInfo(host, port, username, keyFiles), ownsConnectionInfo: true)
         {
@@ -155,7 +151,7 @@ namespace Renci.SshNet
         /// <inheritdoc />
         public void AddForwardedPort(ForwardedPort port)
         {
-            ThrowHelper.ThrowIfNull(port);
+            ArgumentNullException.ThrowIfNull(port);
 
             EnsureSessionIsOpen();
 
@@ -166,7 +162,7 @@ namespace Renci.SshNet
         /// <inheritdoc />
         public void RemoveForwardedPort(ForwardedPort port)
         {
-            ThrowHelper.ThrowIfNull(port);
+            ArgumentNullException.ThrowIfNull(port);
 
             // Stop port forwarding before removing it
             port.Stop();
@@ -325,11 +321,8 @@ namespace Renci.SshNet
 
             if (disposing)
             {
-                if (_inputStream != null)
-                {
-                    _inputStream.Dispose();
-                    _inputStream = null;
-                }
+                _inputStream?.Dispose();
+                _inputStream = null;
 
                 _isDisposed = true;
             }

src/Renci.SshNet/SshCommand.cs

@@ -214,9 +214,9 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException">Either <paramref name="session"/>, <paramref name="commandText"/> is <see langword="null"/>.</exception>
         internal SshCommand(ISession session, string commandText, Encoding encoding)
         {
-            ThrowHelper.ThrowIfNull(session);
-            ThrowHelper.ThrowIfNull(commandText);
-            ThrowHelper.ThrowIfNull(encoding);
+            ArgumentNullException.ThrowIfNull(session);
+            ArgumentNullException.ThrowIfNull(commandText);
+            ArgumentNullException.ThrowIfNull(encoding);
 
             _session = session;
             CommandText = commandText;
@@ -244,7 +244,7 @@ namespace Renci.SshNet
 #pragma warning disable CA1849 // Call async methods when in an async method; PipeStream.DisposeAsync would complete synchronously anyway.
         public Task ExecuteAsync(CancellationToken cancellationToken = default)
         {
-            ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+            ObjectDisposedException.ThrowIf(_isDisposed, this);
 
             if (cancellationToken.IsCancellationRequested)
             {
@@ -385,7 +385,7 @@ namespace Renci.SshNet
         /// <exception cref="SshOperationTimeoutException">Operation has timed out.</exception>
         public IAsyncResult BeginExecute(string commandText, AsyncCallback? callback, object? state)
         {
-            ThrowHelper.ThrowIfNull(commandText);
+            ArgumentNullException.ThrowIfNull(commandText);
 
             CommandText = commandText;
 

src/Renci.SshNet/SshMessageFactory.cs

@@ -184,7 +184,7 @@ namespace Renci.SshNet
 
         public void EnableAndActivateMessage(string messageName)
         {
-            ThrowHelper.ThrowIfNull(messageName);
+            ArgumentNullException.ThrowIfNull(messageName);
 
             lock (_lock)
             {
@@ -208,7 +208,7 @@ namespace Renci.SshNet
 
         public void DisableAndDeactivateMessage(string messageName)
         {
-            ThrowHelper.ThrowIfNull(messageName);
+            ArgumentNullException.ThrowIfNull(messageName);
 
             lock (_lock)
             {

src/Renci.SshNet/SshNetLoggingConfiguration.cs

@@ -1,9 +1,9 @@
 #nullable enable
+using System;
+
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 
-using Renci.SshNet.Common;
-
 namespace Renci.SshNet
 {
     /// <summary>
@@ -19,7 +19,7 @@ namespace Renci.SshNet
         /// <param name="loggerFactory">The logger factory.</param>
         public static void InitializeLogging(ILoggerFactory loggerFactory)
         {
-            ThrowHelper.ThrowIfNull(loggerFactory);
+            ArgumentNullException.ThrowIfNull(loggerFactory);
             LoggerFactory = loggerFactory;
         }
 

src/Renci.SshNet/SubsystemSession.cs

@@ -55,7 +55,7 @@ namespace Renci.SshNet
         {
             get
             {
-                ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+                ObjectDisposedException.ThrowIf(_isDisposed, this);
 
                 return _channel;
             }
@@ -89,8 +89,8 @@ namespace Renci.SshNet
         /// <exception cref="ArgumentNullException"><paramref name="session" /> or <paramref name="subsystemName" /> is <see langword="null"/>.</exception>
         protected SubsystemSession(ISession session, string subsystemName, int operationTimeout)
         {
-            ThrowHelper.ThrowIfNull(session);
-            ThrowHelper.ThrowIfNull(subsystemName);
+            ArgumentNullException.ThrowIfNull(session);
+            ArgumentNullException.ThrowIfNull(subsystemName);
 
             _session = session;
             _subsystemName = subsystemName;
@@ -106,7 +106,7 @@ namespace Renci.SshNet
         /// <exception cref="SshException">The channel session could not be opened, or the subsystem could not be executed.</exception>
         public void Connect()
         {
-            ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+            ObjectDisposedException.ThrowIf(_isDisposed, this);
 
             if (IsOpen)
             {
@@ -166,7 +166,7 @@ namespace Renci.SshNet
         /// <param name="data">The data to be sent.</param>
         public void SendData(byte[] data)
         {
-            ThrowHelper.ThrowObjectDisposedIf(_isDisposed, this);
+            ObjectDisposedException.ThrowIf(_isDisposed, this);
             EnsureSessionIsOpen();
 
             _channel.SendData(data);

test/Renci.SshNet.AotCompatibilityTestApp/Program.cs

@@ -2,7 +2,7 @@
 
 namespace Renci.SshNet.AotCompatibilityTestApp
 {
-    public static class Program
+    internal static class Program
     {
         public static void Main()
         {

test/Renci.SshNet.AotCompatibilityTestApp/Renci.SshNet.AotCompatibilityTestApp.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net9.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <PublishAot>true</PublishAot>
     <SelfContained>true</SelfContained>
     <TrimmerSingleWarn>false</TrimmerSingleWarn>

test/Renci.SshNet.Benchmarks/.editorconfig

@@ -74,10 +74,6 @@ dotnet_diagnostic.MA0026.severity = silent
 
 #### .NET Compiler Platform analysers rules ####
 
-# CA2000: Dispose objects before losing scope
-# https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca2000
-dotnet_diagnostic.CA2000.severity = silent
-
 # IDE0046: Use conditional expression for return
 # https://learn.microsoft.com/en-ca/dotnet/fundamentals/code-analysis/style-rules/ide0046
 dotnet_diagnostic.IDE0046.severity = silent

test/Renci.SshNet.Benchmarks/Renci.SshNet.Benchmarks.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net9.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>