WIP: Implement support for rsa-sha2-256 key exchange.

src/Renci.SshNet/ConnectionInfo.cs

@@ -389,6 +389,7 @@ public ConnectionInfo(string host, int port, string username, ProxyTypes proxyTy
 #endif
                     {"ssh-rsa", data => new KeyHostAlgorithm("ssh-rsa", new RsaKey(), data)},
                     {"ssh-dss", data => new KeyHostAlgorithm("ssh-dss", new DsaKey(), data)},
+                    {"rsa-sha2-256", data => new KeyHostAlgorithm("rsa-sha2-256", new RsaWithSha256SignatureKey(), data)},
                     //{"x509v3-sign-rsa", () => { ... },
                     //{"x509v3-sign-dss", () => { ... },
                     //{"spki-sign-rsa", () => { ... },

src/Renci.SshNet/IPrivateKeySource.cs

@@ -10,6 +10,6 @@ public interface IPrivateKeySource
         /// <summary>
         /// Gets the host key.
         /// </summary>
-        HostAlgorithm HostKey { get; }
+        HostAlgorithm[] HostKeys { get; }
     }
 }

src/Renci.SshNet/PrivateKeyAuthenticationMethod.cs

@@ -4,6 +4,7 @@
 using Renci.SshNet.Messages.Authentication;
 using Renci.SshNet.Messages;
 using Renci.SshNet.Common;
+using Renci.SshNet.Security;
 using System.Threading;
 
 namespace Renci.SshNet
@@ -60,24 +61,38 @@ public override AuthenticationResult Authenticate(Session session)
 
             session.RegisterMessage("SSH_MSG_USERAUTH_PK_OK");
 
+            HostAlgorithm[] hostKeys = new HostAlgorithm[] { };
+
+            foreach (var keyFile in KeyFiles)
+            {
+                var idx = hostKeys.Length;
+
+                Array.Resize(ref hostKeys, idx + keyFile.HostKeys.Length);
+
+                for(int i = 0; i < keyFile.HostKeys.Length; i++)
+                {
+                    hostKeys[idx++] = keyFile.HostKeys[i];
+                }
+            }
+
             try
             {
-                foreach (var keyFile in KeyFiles)
+                foreach (var hostKey in hostKeys)
                 {
                     _authenticationCompleted.Reset();
                     _isSignatureRequired = false;
 
                     var message = new RequestMessagePublicKey(ServiceName.Connection,
                                                               Username,
-                                                              keyFile.HostKey.Name,
-                                                              keyFile.HostKey.Data);
+                                                              hostKey.Name,
+                                                              hostKey.Data);
 
-                    if (KeyFiles.Count < 2)
+                    if (hostKeys.Length < 2)
                     {
                         //  If only one key file provided then send signature for very first request
                         var signatureData = new SignatureData(message, session.SessionId).GetBytes();
 
-                        message.Signature = keyFile.HostKey.Sign(signatureData);
+                        message.Signature = hostKey.Sign(signatureData);
                     }
 
                     //  Send public key authentication request
@@ -91,12 +106,12 @@ public override AuthenticationResult Authenticate(Session session)
 
                         var signatureMessage = new RequestMessagePublicKey(ServiceName.Connection,
                                                                            Username,
-                                                                           keyFile.HostKey.Name,
-                                                                           keyFile.HostKey.Data);
+                                                                           hostKey.Name,
+                                                                           hostKey.Data);
 
                         var signatureData = new SignatureData(message, session.SessionId).GetBytes();
 
-                        signatureMessage.Signature = keyFile.HostKey.Sign(signatureData);
+                        signatureMessage.Signature = hostKey.Sign(signatureData);
 
                         //  Send public key authentication request with signature
                         session.SendMessage(signatureMessage);

src/Renci.SshNet/PrivateKeyFile.cs

@@ -77,15 +77,15 @@ public class PrivateKeyFile : IPrivateKeySource, IDisposable
         /// <summary>
         /// Gets the host key.
         /// </summary>
-        public HostAlgorithm HostKey { get; private set; }
+        public HostAlgorithm[] HostKeys { get; private set; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="PrivateKeyFile"/> class.
         /// </summary>
         /// <param name="key">The key.</param>
         public PrivateKeyFile(Key key)
         {
-            HostKey = new KeyHostAlgorithm(key.ToString(), key);
+            HostKeys = new KeyHostAlgorithm[] { new KeyHostAlgorithm(key.ToString(), key) };
         }
 
         /// <summary>
@@ -214,22 +214,24 @@ private void Open(Stream privateKey, string passPhrase)
             switch (keyName)
             {
                 case "RSA":
-                    _key = new RsaKey(decryptedData);
-                    HostKey = new KeyHostAlgorithm("ssh-rsa", _key);
+                    HostKeys = new KeyHostAlgorithm[] {
+                        new KeyHostAlgorithm("rsa-sha2-256", new RsaWithSha256SignatureKey(decryptedData)),
+                        new KeyHostAlgorithm("ssh-rsa", new RsaKey(decryptedData)),
+                    };
                     break;
                 case "DSA":
                     _key = new DsaKey(decryptedData);
-                    HostKey = new KeyHostAlgorithm("ssh-dss", _key);
+                    HostKeys = new KeyHostAlgorithm[] { new KeyHostAlgorithm("ssh-dss", _key) };
                     break;
 #if FEATURE_ECDSA
                 case "EC":
                     _key = new EcdsaKey(decryptedData);
-                    HostKey = new KeyHostAlgorithm(_key.ToString(), _key);
+                    HostKeys = new KeyHostAlgorithm[] { new KeyHostAlgorithm(_key.ToString(), _key) };
                     break;
 #endif
                 case "OPENSSH":
                     _key = ParseOpenSshV1Key(decryptedData, passPhrase);
-                    HostKey = new KeyHostAlgorithm(_key.ToString(), _key);
+                    HostKeys = new KeyHostAlgorithm[] { new KeyHostAlgorithm(_key.ToString(), _key) };
                     break;
                 case "SSH2 ENCRYPTED":
                     var reader = new SshDataReader(decryptedData);
@@ -281,7 +283,7 @@ private void Open(Stream privateKey, string passPhrase)
                         var q = reader.ReadBigIntWithBits();//p
                         var p = reader.ReadBigIntWithBits();//q
                         _key = new RsaKey(modulus, exponent, d, p, q, inverseQ);
-                        HostKey = new KeyHostAlgorithm("ssh-rsa", _key);
+                        HostKeys = new KeyHostAlgorithm[] { new KeyHostAlgorithm("ssh-rsa", _key) };
                     }
                     else if (keyType == "dl-modp{sign{dsa-nist-sha1},dh{plain}}")
                     {
@@ -296,7 +298,7 @@ private void Open(Stream privateKey, string passPhrase)
                         var y = reader.ReadBigIntWithBits();
                         var x = reader.ReadBigIntWithBits();
                         _key = new DsaKey(p, q, g, y, x);
-                        HostKey = new KeyHostAlgorithm("ssh-dss", _key);
+                        HostKeys = new KeyHostAlgorithm[] { new KeyHostAlgorithm("ssh-dss", _key) };
                     }
                     else
                     {

src/Renci.SshNet/Security/Cryptography/RsaSha256DigitalSignature.cs

@@ -0,0 +1,84 @@
+using System;
+using System.Security.Cryptography;
+using Renci.SshNet.Abstractions;
+using Renci.SshNet.Common;
+using Renci.SshNet.Security.Cryptography.Ciphers;
+
+namespace Renci.SshNet.Security.Cryptography
+{
+    /// <summary>
+    /// Implements RSA digital signature algorithm.
+    /// </summary>
+    public class RsaSha256DigitalSignature : CipherDigitalSignature, IDisposable
+    {
+        private HashAlgorithm _hash;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RsaSha256DigitalSignature"/> class.
+        /// </summary>
+        /// <param name="rsaKey">The RSA key.</param>
+        public RsaSha256DigitalSignature(RsaWithSha256SignatureKey rsaKey)
+            : base(new ObjectIdentifier(2, 16, 840, 1, 101, 3, 4, 2, 1), new RsaCipher(rsaKey))
+        {
+            _hash = SHA256.Create();
+        }
+
+        /// <summary>
+        /// Hashes the specified input.
+        /// </summary>
+        /// <param name="input">The input.</param>
+        /// <returns>
+        /// Hashed data.
+        /// </returns>
+        protected override byte[] Hash(byte[] input)
+        {
+            return _hash.ComputeHash(input);
+        }
+
+        #region IDisposable Members
+
+        private bool _isDisposed;
+
+        /// <summary>
+        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
+        /// </summary>
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        /// <summary>
+        /// Releases unmanaged and - optionally - managed resources
+        /// </summary>
+        /// <param name="disposing"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
+        protected virtual void Dispose(bool disposing)
+        {
+            if (_isDisposed)
+                return;
+
+            if (disposing)
+            {
+                var hash = _hash;
+                if (hash != null)
+                {
+                    hash.Dispose();
+                    _hash = null;
+                }
+
+                _isDisposed = true;
+            }
+        }
+
+        /// <summary>
+        /// Releases unmanaged resources and performs other cleanup operations before the
+        /// <see cref="RsaSha256DigitalSignature"/> is reclaimed by garbage collection.
+        /// </summary>
+        ~RsaSha256DigitalSignature()
+        {
+            Dispose(false);
+        }
+
+        #endregion
+    }
+}

src/Renci.SshNet/Security/Cryptography/RsaWithSha256SignatureKey.cs

@@ -0,0 +1,69 @@
+using System;
+using Renci.SshNet.Common;
+using Renci.SshNet.Security.Cryptography;
+
+namespace Renci.SshNet.Security
+{
+    /// <summary>
+    /// Contains RSA private and public key
+    /// </summary>
+    public class RsaWithSha256SignatureKey : RsaKey
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RsaWithSha256SignatureKey"/> class.
+        /// </summary>
+        public RsaWithSha256SignatureKey()
+        { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RsaWithSha256SignatureKey"/> class.
+        /// </summary>
+        /// <param name="data">DER encoded private key data.</param>
+        public RsaWithSha256SignatureKey(byte[] data)
+            : base(data)
+        {
+            if (_privateKey.Length != 8)
+                throw new InvalidOperationException("Invalid private key.");
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RsaWithSha256SignatureKey"/> class.
+        /// </summary>
+        /// <param name="modulus">The modulus.</param>
+        /// <param name="exponent">The exponent.</param>
+        /// <param name="d">The d.</param>
+        /// <param name="p">The p.</param>
+        /// <param name="q">The q.</param>
+        /// <param name="inverseQ">The inverse Q.</param>
+        public RsaWithSha256SignatureKey(BigInteger modulus, BigInteger exponent, BigInteger d, BigInteger p, BigInteger q,
+            BigInteger inverseQ) : base(modulus, exponent, d, p, q, inverseQ)
+        {
+        }
+
+        private RsaSha256DigitalSignature _digitalSignature;
+
+        /// <summary>
+        /// Gets the digital signature.
+        /// </summary>
+        protected override DigitalSignature DigitalSignature
+        {
+            get
+            {
+                if (_digitalSignature == null)
+                {
+                    _digitalSignature = new RsaSha256DigitalSignature(this);
+                }
+
+                return _digitalSignature;
+            }
+        }
+
+        /// <summary>
+        /// Gets the Key String.
+        /// </summary>
+        public override string ToString()
+        {
+            return "rsa-sha2-256";
+        }
+    }
+}