Add support for OpenSSL PKCS#8 private key format (#1496)

* Add support for OpenSSL PKCS#8 private key format

* Update comments

* Convert public key to ssh format

* Convert existing keys instead of generate new keys; Use DataRow for testing

* Minimize the change

* Minimize the change

* Fix build

test/Data/Key.DSA.PKCS8.Encrypted.Aes.256.CBC.12345.txt

@@ -0,0 +1,12 @@
+-----BEGIN ENCRYPTED PRIVATE KEY-----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+-----END ENCRYPTED PRIVATE KEY-----

test/Data/Key.DSA.PKCS8.txt

@@ -0,0 +1,9 @@
+-----BEGIN PRIVATE KEY-----
+MIIBSgIBADCCASsGByqGSM44BAEwggEeAoGBALVl3fae2O4qwsAK95SUShX0KMUN
+P+yl/uT3lGH9T/ZptnHSlrTxnTWXCl0g91KEeCaEnDDhLxm4aCv1Ag4B/yvcM4u3
+4qkmaNLy2LiAxiqdobZcNG61Pqwqd5IDkp38LBsn8tmb12xu9NalpUfOiSEB1cyC
+r4zFZMrm0wtdyJQVAhUArvojZKn/2DgGI2Kx0ghxZlgHxGECgYAOVJ434UAR3Hn6
+lA5nWNfFOuUVH3W7nJaP0FQJiIPx7GUbdxO9qtDNTbWkWL3c9qx5+B7Ole4xM7cv
+yXPrNQUYDHCFlS+Ue2x3IeJrkdfZkH9ePP25y5A0J4/c+8XXvQaj4zA5nfw13oy5
+Ptyd7d3Kq5tEDM8KiVdIhwkXjUA3PQQWAhQYRjs5PgIpnqG/euBPPh7EDZcnXg==
+-----END PRIVATE KEY-----

test/Data/Key.ECDSA.PKCS8.Encrypted.Aes.256.CBC.12345.txt

@@ -0,0 +1,7 @@
+-----BEGIN ENCRYPTED PRIVATE KEY-----
+MIHsMFcGCSqGSIb3DQEFDTBKMCkGCSqGSIb3DQEFDDAcBAithDR1n5wCYQICCAAw
+DAYIKoZIhvcNAgkFADAdBglghkgBZQMEASoEEMSzAQ3FSZ5hQHbmb7K9aB0EgZCS
+RVfVmMp1SBllrUMvdMEz5Zwvthaa1/M3Mc6MEVEzgROEXY3X+ywECU9q18aIOct+
+m5bmFcRcwoxo/hj6fsnmeH567KRfnN4Al219azq5ccwTr68y8tasYsZHOFCkn3ve
+Hkzu0+gylHZGWqo5TWif9O9DrII/KszsoX86jJxhORwqCnxMmKQQ/gGvexpAYJA=
+-----END ENCRYPTED PRIVATE KEY-----

test/Data/Key.ECDSA.PKCS8.txt

@@ -0,0 +1,5 @@
+-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgR2poUqAkEiJtWPJS
+HW/tjfkvAhAmuhx1NpgUvCXuIHShRANCAARAPkw7+f3KpINOzPDNWkCkvHlJAV5w
+Tll8OSDGpV0dB5ybUEA+jNnh4oY2EqfvaFPv2YuWn0ddf6g0Ry5VPzcf
+-----END PRIVATE KEY-----

test/Data/Key.OPENSSH.ED25519.PKCS8.Encrypted.Aes.256.CBC.12345.txt

@@ -0,0 +1,6 @@
+-----BEGIN ENCRYPTED PRIVATE KEY-----
+MIGbMFcGCSqGSIb3DQEFDTBKMCkGCSqGSIb3DQEFDDAcBAhiAnoQd2VMZwICCAAw
+DAYIKoZIhvcNAgkFADAdBglghkgBZQMEASoEENed/l3AFuDblxDnswMZXDcEQIpo
+fCVdEbDerN0Rrh9i+Ymu+qpEqGlc6jycwR3rPtyL9jy0k5kauBxRn3Z5uCSlGzJL
+JXxlMR+DWG6QDJdxrHI=
+-----END ENCRYPTED PRIVATE KEY-----

test/Data/Key.OPENSSH.ED25519.PKCS8.txt

@@ -0,0 +1,3 @@
+-----BEGIN PRIVATE KEY-----
+MC4CAQAwBQYDK2VwBCIEIADMEXUw9TGuz7JykmHbzPOj8XebpZwo76iuxJtHkvAp
+-----END PRIVATE KEY-----

test/Data/Key.RSA.PKCS8.Encrypted.Aes.256.CBC.12345.txt

@@ -0,0 +1,30 @@
+-----BEGIN ENCRYPTED PRIVATE KEY-----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+-----END ENCRYPTED PRIVATE KEY-----

test/Data/Key.RSA.PKCS8.txt

@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----