DSA is removed at compile time from OpenSSH 9.8 and higher.
That means we can no longer test it in our integration tests. It seems like a
good time to remove it. From the OpenSSH release notes:
DSA, as specified in the SSHv2 protocol, is inherently weak - being
limited to a 160 bit private key and use of the SHA1 digest. Its
estimated security level is only 80 bits symmetric equivalent.
OpenSSH has disabled DSA keys by default since 2015 but has retained
run-time optional support for them. DSA was the only mandatory-to-
implement algorithm in the SSHv2 RFCs, mostly because alternative
algorithms were encumbered by patents when the SSHv2 protocol was
specified.
This has not been the case for decades at this point and better
algorithms are well supported by all actively-maintained SSH
implementations. We do not consider the costs of maintaining DSA
in OpenSSH to be justified and hope that removing it from OpenSSH
can accelerate its wider deprecation in supporting cryptography
libraries.
* Use BouncyCastle ECDsa when runtime is Mono
* Falls back to use BouncyCastle if CngKey.Import throws NotImplementedException (in Mono)
* Take NETStandard into consideration
* Adjust some comments
* Change #if NETFRAEWORK to #if NET462 for CngKey
* Separate implementations
* Consolidate Ecdsa property and HashAlgorithm property
* Rename Import_Cng and Import_Bcl to Import; Rename Export_Cng and Export_Bcl to Export;
* Add comments
* refactor
* add host key tests
---------
Co-authored-by: Robert Hague <rh@johnstreetcapital.com>
Co-authored-by: Rob Hague <rob.hague00@gmail.com>
* Use System.Security.Cryptography for DSA
This is the analogue of the RSA change #1373 for DSA. This has a couple of caveats:
- The BCL supports only FIPS 186-compliant keys, that is, public (P, Q) lengths
of (512 <= P <= 1024, 160) for FIPS 186-1/186-2; and (2048, 256), (3072, 256)
for FIPS 186-3/186-4. The latter also specifies (2048, 224) but due to a quirk
in the Windows API, the BCL does not support Q values of length 224[^1].
- OpenSSH, based on the SSH spec, only supports (supported) Q values of length 160,
but appears to also work in non-FIPS-compliant cases such as in our integration
tests with a (2048, 160) host key. That test now fails and I changed that host key
to (1024, 160).
This basically means that (1024, 160) is the largest DSA key size supported by both
SSH.NET and OpenSSH. However, given that OpenSSH deprecated DSA in 2015[^2], and the
alternative that I have been considering is just to delete support for DSA in the
library, this change seems reasonable to me. I don't think we can justify keeping the
current handwritten code around.
I think we may still consider dropping DSA from the library, I just had this branch
laying around and figured I'd finish it off.
[^1]: https://github.com/dotnet/runtime/blob/fadd8313653f71abd0068c8bf914be88edb2c8d3/src/libraries/Common/src/System/Security/Cryptography/DSACng.ImportExport.cs#L259-L265
[^2]: https://www.openssh.com/txt/release-7.0
* Appease mono
* test experiment
* Revert "Appease mono"
This reverts commit 881eefe5e8.
* Move test projects to test folder.
Move global.json to root of repo.
Update solution items in solution.
* Move test projects to test folder.
Move global.json to root of repo.
Update solution items in solution.
Update appveyor configuration/
* Attempt to have appveyor use the correct .NET SDK.
* Update .NET SDK to version 7.0.402.
* Move Data folder below Renci.SshNet.Tests.
* Make csinst less chatty.
* Move Data folder directly below test folder as it's used by multiple test projects.
* Remove CS1591 nowarn from concrete test projects as this is already defined in the Directory.Build.props that is in the test folder.
* Fix integration test after moving test projects
---------
Co-authored-by: drieseng <gert.driesen@telenet.be>
Rob Hague