From e3d3796d33537e50efe2446bb8630b95a975a3bf Mon Sep 17 00:00:00 2001
From: olegkap_cp <olegkap@gmail.com>
Date: Wed, 13 Jul 2011 14:41:13 +0000
Subject: [PATCH] Fix Aes -ctr algorithms Move hmac-md5 hashing algorithm into
 library

---
 .../Renci.SshNet.Silverlight.csproj           |   9 +
 .../Renci.SshNet/ConnectionInfo.cs            |   2 +-
 .../Renci.SshNet/Renci.SshNet.csproj          |  11 +-
 .../Renci.SshNet/Security/CipherAESCTR.cs     |   2 +-
 .../Security/Cryptography/HMAC.cs             | 142 +++++++
 .../Renci.SshNet/Security/Cryptography/MD5.cs | 383 ++++++++++++++++++
 Renci.SshClient/Renci.SshNet/Security/HMac.cs |   2 +-
 .../Renci.SshNet/Security/HMacMD5.cs          |  15 +-
 .../Renci.SshNet/Security/HMacSha1.cs         |  13 +-
 9 files changed, 565 insertions(+), 14 deletions(-)
 create mode 100644 Renci.SshClient/Renci.SshNet/Security/Cryptography/HMAC.cs
 create mode 100644 Renci.SshClient/Renci.SshNet/Security/Cryptography/MD5.cs

diff --git a/Renci.SshClient/Renci.SshNet.Silverlight/Renci.SshNet.Silverlight.csproj b/Renci.SshClient/Renci.SshNet.Silverlight/Renci.SshNet.Silverlight.csproj
index 95aabd6c..e2bc6a9a 100644
--- a/Renci.SshClient/Renci.SshNet.Silverlight/Renci.SshNet.Silverlight.csproj
+++ b/Renci.SshClient/Renci.SshNet.Silverlight/Renci.SshNet.Silverlight.csproj
@@ -441,6 +441,12 @@
     <Compile Include="..\Renci.SshNet\Security\Cryptography\Ciphers\TwofishCipher.cs">
       <Link>Security\Cryptography\Ciphers\TwofishCipher.cs</Link>
     </Compile>
+    <Compile Include="..\Renci.SshNet\Security\Cryptography\HMAC.cs">
+      <Link>Security\Cryptography\HMAC.cs</Link>
+    </Compile>
+    <Compile Include="..\Renci.SshNet\Security\Cryptography\MD5.cs">
+      <Link>Security\Cryptography\MD5.cs</Link>
+    </Compile>
     <Compile Include="..\Renci.SshNet\Security\Cryptography\Modes\CbcMode.cs">
       <Link>Security\Cryptography\Modes\CbcMode.cs</Link>
     </Compile>
@@ -483,6 +489,9 @@
     <Compile Include="..\Renci.SshNet\Security\HMac.cs">
       <Link>Security\HMac.cs</Link>
     </Compile>
+    <Compile Include="..\Renci.SshNet\Security\HMacMD5.cs">
+      <Link>Security\HMacMD5.cs</Link>
+    </Compile>
     <Compile Include="..\Renci.SshNet\Security\HMacSha1.cs">
       <Link>Security\HMacSha1.cs</Link>
     </Compile>
diff --git a/Renci.SshClient/Renci.SshNet/ConnectionInfo.cs b/Renci.SshClient/Renci.SshNet/ConnectionInfo.cs
index d0860f6a..01e6a5d6 100644
--- a/Renci.SshClient/Renci.SshNet/ConnectionInfo.cs
+++ b/Renci.SshClient/Renci.SshNet/ConnectionInfo.cs
@@ -199,9 +199,9 @@ namespace Renci.SshNet
         /// <param name="host">Connection host.</param>
         /// <param name="port">Connection port.</param>
         /// <param name="username">Connection username.</param>
-        /// <exception cref="ArgumentNullException"><paramref name="password"/> is null.</exception>
         /// <exception cref="ArgumentException"><paramref name="host"/> is invalid, or <paramref name="username"/> is null or contains whitespace characters.</exception>
         /// <exception cref="ArgumentOutOfRangeException"><paramref name="port"/> is not within <see cref="IPEndPoint.MinPort"/> and <see cref="IPEndPoint.MaxPort"/>.</exception>
+        /// <exception cref="ArgumentException"><paramref name="username"/> is null or empty.</exception>
         protected ConnectionInfo(string host, int port, string username)
             : this()
         {
diff --git a/Renci.SshClient/Renci.SshNet/Renci.SshNet.csproj b/Renci.SshClient/Renci.SshNet/Renci.SshNet.csproj
index 7d7dcfb9..d9b81b6a 100644
--- a/Renci.SshClient/Renci.SshNet/Renci.SshNet.csproj
+++ b/Renci.SshClient/Renci.SshNet/Renci.SshNet.csproj
@@ -130,6 +130,12 @@
     <Compile Include="Security\CipherTripleDesCbc.cs">
       <SubType>Code</SubType>
     </Compile>
+    <Compile Include="Security\Cryptography\HMAC.cs">
+      <SubType>Code</SubType>
+    </Compile>
+    <Compile Include="Security\Cryptography\MD5.cs">
+      <SubType>Code</SubType>
+    </Compile>
     <Compile Include="Security\CryptoKey.cs">
       <SubType>Code</SubType>
     </Compile>
@@ -157,9 +163,7 @@
     <Compile Include="Security\HMacMD5.cs">
       <SubType>Code</SubType>
     </Compile>
-    <Compile Include="Security\HMacSha1.cs">
-      <SubType>Code</SubType>
-    </Compile>
+    <Compile Include="Security\HMacSha1.cs" />
     <Compile Include="Security\KeyExchange.cs">
       <SubType>Code</SubType>
     </Compile>
@@ -381,7 +385,6 @@
   <ItemGroup>
     <Content Include="Documentation\SshClient.shfbproj" />
   </ItemGroup>
-  <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
diff --git a/Renci.SshClient/Renci.SshNet/Security/CipherAESCTR.cs b/Renci.SshClient/Renci.SshNet/Security/CipherAESCTR.cs
index 6e143c21..1e122115 100644
--- a/Renci.SshClient/Renci.SshNet/Security/CipherAESCTR.cs
+++ b/Renci.SshClient/Renci.SshNet/Security/CipherAESCTR.cs
@@ -22,7 +22,7 @@ namespace Renci.SshNet.Security
         {
             get
             {
-                return this._keySize / 8;
+                return this._keySize;
             }
         }
 
diff --git a/Renci.SshClient/Renci.SshNet/Security/Cryptography/HMAC.cs b/Renci.SshClient/Renci.SshNet/Security/Cryptography/HMAC.cs
new file mode 100644
index 00000000..a3bf901f
--- /dev/null
+++ b/Renci.SshClient/Renci.SshNet/Security/Cryptography/HMAC.cs
@@ -0,0 +1,142 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Security.Cryptography;
+
+namespace Renci.SshNet.Security.Cryptography
+{
+    /// <summary>
+    /// Provides HMAC algorithm implementation.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    public class HMAC<T> : KeyedHashAlgorithm where T : HashAlgorithm, new()
+    {
+        private HashAlgorithm _hash;
+        private bool _isHashing;
+        private byte[] _innerPadding;
+        private byte[] _outerPadding;
+
+        /// <summary>
+        /// Gets the size of the block.
+        /// </summary>
+        /// <value>
+        /// The size of the block.
+        /// </value>
+        protected int BlockSize
+        {
+            get
+            {
+                return this._hash.InputBlockSize;
+            }
+        }
+
+        /// <summary>
+        /// Rfc 2104.
+        /// </summary>
+        /// <param name="key">The key.</param>
+        public HMAC(byte[] key)
+        {
+            // Create the hash algorithms.
+            this._hash = new T();
+
+            this.HashSizeValue = this._hash.HashSize;
+
+            this.Key = key;
+
+            this.Initialize();
+        }
+
+        /// <summary>
+        /// 
+        /// </summary>
+        public override byte[] Key
+        {
+            get { return (byte[])KeyValue.Clone(); }
+            set
+            {
+                if (this._isHashing)
+                {
+                    throw new Exception("Cannot change key during hash operation");
+                }
+                if (value.Length > this.BlockSize)
+                {
+                    this.KeyValue = this._hash.ComputeHash(value);
+                    // No need to call Initialize, ComputeHash does it automatically.
+                }
+                else
+                {
+                    this.KeyValue = value.Clone() as byte[];
+                }
+
+                this._innerPadding = new byte[this.BlockSize];
+                this._outerPadding = new byte[this.BlockSize];
+
+                // Compute inner and outer padding.
+                int i = 0;
+                for (i = 0; i < 64; i++)
+                {
+                    this._innerPadding[i] = 0x36;
+                    this._outerPadding[i] = 0x5C;
+                }
+                for (i = 0; i < this.KeyValue.Length; i++)
+                {
+                    this._innerPadding[i] ^= this.KeyValue[i];
+                    this._outerPadding[i] ^= this.KeyValue[i];
+                }
+            }
+        }
+
+        /// <summary>
+        /// 
+        /// </summary>
+        public override void Initialize()
+        {
+            this._isHashing = false;
+        }
+
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="rgb"></param>
+        /// <param name="ib"></param>
+        /// <param name="cb"></param>
+        protected override void HashCore(byte[] rgb, int ib, int cb)
+        {
+            if (!this._isHashing)
+            {
+                this._hash.TransformBlock(this._innerPadding, 0, this.BlockSize, this._innerPadding, 0);
+                this._isHashing = true;
+            }
+            this._hash.TransformBlock(rgb, ib, cb, rgb, ib);
+        }
+
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <returns></returns>
+        protected override byte[] HashFinal()
+        {
+            if (!this._isHashing)
+            {
+                this._hash.TransformBlock(this._innerPadding, 0, 64, this._innerPadding, 0);
+                this._isHashing = true;
+            }
+
+            // Finalize the original hash.
+            this._hash.TransformFinalBlock(new byte[0], 0, 0);
+
+            var hashValue = this._hash.Hash;
+
+            // Write the outer array.
+            this._hash.TransformBlock(this._outerPadding, 0, this.BlockSize, this._outerPadding, 0);
+
+            // Write the inner hash and finalize the hash.            
+            this._hash.TransformFinalBlock(hashValue, 0, hashValue.Length);
+
+            this._isHashing = false;
+
+            return this._hash.Hash;
+        }        
+    }
+}
diff --git a/Renci.SshClient/Renci.SshNet/Security/Cryptography/MD5.cs b/Renci.SshClient/Renci.SshNet/Security/Cryptography/MD5.cs
new file mode 100644
index 00000000..fca283a9
--- /dev/null
+++ b/Renci.SshClient/Renci.SshNet/Security/Cryptography/MD5.cs
@@ -0,0 +1,383 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Security.Cryptography;
+
+namespace Renci.SshNet.Security.Cryptography
+{
+    /// <summary>
+    /// MD5 algorithm implementation
+    /// </summary>
+    public class MD5 : HashAlgorithm
+    {
+        private byte[] _buffer = new byte[4];
+        private int _bufferOffset;
+        private long _byteCount;
+        private int H1, H2, H3, H4;         // IV's
+        private int[] _hashValue = new int[16];
+        private int _offset;
+
+        /// <summary>
+        /// Gets the size, in bits, of the computed hash code.
+        /// </summary>
+        /// <returns>The size, in bits, of the computed hash code.</returns>
+        public override int HashSize
+        {
+            get
+            {
+                return 128;
+            }
+        }
+
+        /// <summary>
+        /// Gets the input block size.
+        /// </summary>
+        /// <returns>The input block size.</returns>
+        public override int InputBlockSize
+        {
+            get
+            {
+                return 64;
+            }
+        }
+
+        /// <summary>
+        /// Gets the output block size.
+        /// </summary>
+        /// <returns>The output block size.</returns>
+        public override int OutputBlockSize
+        {
+            get
+            {
+                return 64;
+            }
+        }
+
+        /// <summary>
+        /// Gets a value indicating whether the current transform can be reused.
+        /// </summary>
+        /// <returns>Always true.</returns>
+        public override bool CanReuseTransform
+        {
+            get
+            {
+                return true;
+            }
+        }
+
+        /// <summary>
+        /// Gets a value indicating whether multiple blocks can be transformed.
+        /// </summary>
+        /// <returns>true if multiple blocks can be transformed; otherwise, false.</returns>
+        public override bool CanTransformMultipleBlocks
+        {
+            get
+            {
+                return true;
+            }
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="MD5"/> class.
+        /// </summary>
+        public MD5()
+        {
+            this.Initialize();
+        }
+
+        /// <summary>
+        /// Routes data written to the object into the hash algorithm for computing the hash.
+        /// </summary>
+        /// <param name="array">The input to compute the hash code for.</param>
+        /// <param name="ibStart">The offset into the byte array from which to begin using data.</param>
+        /// <param name="cbSize">The number of bytes in the byte array to use as data.</param>
+        protected override void HashCore(byte[] array, int ibStart, int cbSize)
+        {
+            //  Fill the current word
+            while ((this._bufferOffset != 0) && (cbSize > 0))
+            {
+                this.Update(array[ibStart]);
+                ibStart++;
+                cbSize--;
+            }
+
+            //  Process whole words.
+            while (cbSize > this._buffer.Length)
+            {
+                this.ProcessWord(array, ibStart);
+
+                ibStart += this._buffer.Length;
+                cbSize -= this._buffer.Length;
+                this._byteCount += this._buffer.Length;
+            }
+
+            //  Load in the remainder.
+            while (cbSize > 0)
+            {
+                this.Update(array[ibStart]);
+
+                ibStart++;
+                cbSize--;
+            }
+        }
+
+        /// <summary>
+        /// Finalizes the hash computation after the last data is processed by the cryptographic stream object.
+        /// </summary>
+        /// <returns>
+        /// The computed hash code.
+        /// </returns>
+        protected override byte[] HashFinal()
+        {
+            long bitLength = (this._byteCount << 3);
+
+            //  Add the pad bytes.
+            this.Update((byte)128);
+
+            while (this._bufferOffset != 0)
+                this.Update((byte)0);
+
+            if (this._offset > 14)
+            {
+                this.ProcessBlock();
+            }
+
+            this._hashValue[14] = (int)(bitLength & 0xffffffff);
+            this._hashValue[15] = (int)((ulong)bitLength >> 32);
+
+            this.ProcessBlock();
+
+            var output = new byte[16];
+
+            this.UnpackWord(H1, output, 0);
+            this.UnpackWord(H2, output, 0 + 4);
+            this.UnpackWord(H3, output, 0 + 8);
+            this.UnpackWord(H4, output, 0 + 12);
+
+            this.Initialize();
+
+            return output;
+        }
+
+        /// <summary>
+        /// Initializes an implementation of the <see cref="T:System.Security.Cryptography.HashAlgorithm"/> class.
+        /// </summary>
+        public override void Initialize()
+        {
+            this._byteCount = 0;
+            this._bufferOffset = 0;
+            Array.Clear(this._buffer, 0, this._buffer.Length);
+
+            H1 = unchecked((int)0x67452301);
+            H2 = unchecked((int)0xefcdab89);
+            H3 = unchecked((int)0x98badcfe);
+            H4 = unchecked((int)0x10325476);
+
+            this._offset = 0;
+
+            for (int i = 0; i != this._hashValue.Length; i++)
+            {
+                this._hashValue[i] = 0;
+            }
+        }
+
+        private void Update(byte input)
+        {
+            this._buffer[this._bufferOffset++] = input;
+
+            if (this._bufferOffset == this._buffer.Length)
+            {
+                this.ProcessWord(this._buffer, 0);
+                this._bufferOffset = 0;
+            }
+
+            this._byteCount++;
+        }
+
+        private void ProcessWord(byte[] input, int inOff)
+        {
+            this._hashValue[this._offset++] = (input[inOff] & 0xff) | ((input[inOff + 1] & 0xff) << 8)
+                | ((input[inOff + 2] & 0xff) << 16) | ((input[inOff + 3] & 0xff) << 24);
+
+            if (this._offset == 16)
+            {
+                ProcessBlock();
+            }
+        }
+
+        private void UnpackWord(int word, byte[] outBytes, int outOff)
+        {
+            outBytes[outOff] = (byte)word;
+            outBytes[outOff + 1] = (byte)((uint)word >> 8);
+            outBytes[outOff + 2] = (byte)((uint)word >> 16);
+            outBytes[outOff + 3] = (byte)((uint)word >> 24);
+        }
+
+        //
+        // round 1 left rotates
+        //
+        private static readonly int S11 = 7;
+        private static readonly int S12 = 12;
+        private static readonly int S13 = 17;
+        private static readonly int S14 = 22;
+
+        //
+        // round 2 left rotates
+        //
+        private static readonly int S21 = 5;
+        private static readonly int S22 = 9;
+        private static readonly int S23 = 14;
+        private static readonly int S24 = 20;
+
+        //
+        // round 3 left rotates
+        //
+        private static readonly int S31 = 4;
+        private static readonly int S32 = 11;
+        private static readonly int S33 = 16;
+        private static readonly int S34 = 23;
+
+        //
+        // round 4 left rotates
+        //
+        private static readonly int S41 = 6;
+        private static readonly int S42 = 10;
+        private static readonly int S43 = 15;
+        private static readonly int S44 = 21;
+
+        /*
+        * rotate int x left n bits.
+        */
+        private int RotateLeft(int x, int n)
+        {
+            return (x << n) | (int)((uint)x >> (32 - n));
+        }
+
+        /*
+        * F, G, H and I are the basic MD5 functions.
+        */
+        private int F(int u, int v, int w)
+        {
+            return (u & v) | (~u & w);
+        }
+
+        private int G(int u, int v, int w)
+        {
+            return (u & w) | (v & ~w);
+        }
+
+        private int H(int u, int v, int w)
+        {
+            return u ^ v ^ w;
+        }
+
+        private int K(int u, int v, int w)
+        {
+            return v ^ (u | ~w);
+        }
+
+        private void ProcessBlock()
+        {
+            int a = H1;
+            int b = H2;
+            int c = H3;
+            int d = H4;
+
+            //
+            // Round 1 - F cycle, 16 times.
+            //
+            a = RotateLeft((a + F(b, c, d) + this._hashValue[0] + unchecked((int)0xd76aa478)), S11) + b;
+            d = RotateLeft((d + F(a, b, c) + this._hashValue[1] + unchecked((int)0xe8c7b756)), S12) + a;
+            c = RotateLeft((c + F(d, a, b) + this._hashValue[2] + unchecked((int)0x242070db)), S13) + d;
+            b = RotateLeft((b + F(c, d, a) + this._hashValue[3] + unchecked((int)0xc1bdceee)), S14) + c;
+            a = RotateLeft((a + F(b, c, d) + this._hashValue[4] + unchecked((int)0xf57c0faf)), S11) + b;
+            d = RotateLeft((d + F(a, b, c) + this._hashValue[5] + unchecked((int)0x4787c62a)), S12) + a;
+            c = RotateLeft((c + F(d, a, b) + this._hashValue[6] + unchecked((int)0xa8304613)), S13) + d;
+            b = RotateLeft((b + F(c, d, a) + this._hashValue[7] + unchecked((int)0xfd469501)), S14) + c;
+            a = RotateLeft((a + F(b, c, d) + this._hashValue[8] + unchecked((int)0x698098d8)), S11) + b;
+            d = RotateLeft((d + F(a, b, c) + this._hashValue[9] + unchecked((int)0x8b44f7af)), S12) + a;
+            c = RotateLeft((c + F(d, a, b) + this._hashValue[10] + unchecked((int)0xffff5bb1)), S13) + d;
+            b = RotateLeft((b + F(c, d, a) + this._hashValue[11] + unchecked((int)0x895cd7be)), S14) + c;
+            a = RotateLeft((a + F(b, c, d) + this._hashValue[12] + unchecked((int)0x6b901122)), S11) + b;
+            d = RotateLeft((d + F(a, b, c) + this._hashValue[13] + unchecked((int)0xfd987193)), S12) + a;
+            c = RotateLeft((c + F(d, a, b) + this._hashValue[14] + unchecked((int)0xa679438e)), S13) + d;
+            b = RotateLeft((b + F(c, d, a) + this._hashValue[15] + unchecked((int)0x49b40821)), S14) + c;
+
+            //
+            // Round 2 - G cycle, 16 times.
+            //
+            a = RotateLeft((a + G(b, c, d) + this._hashValue[1] + unchecked((int)0xf61e2562)), S21) + b;
+            d = RotateLeft((d + G(a, b, c) + this._hashValue[6] + unchecked((int)0xc040b340)), S22) + a;
+            c = RotateLeft((c + G(d, a, b) + this._hashValue[11] + unchecked((int)0x265e5a51)), S23) + d;
+            b = RotateLeft((b + G(c, d, a) + this._hashValue[0] + unchecked((int)0xe9b6c7aa)), S24) + c;
+            a = RotateLeft((a + G(b, c, d) + this._hashValue[5] + unchecked((int)0xd62f105d)), S21) + b;
+            d = RotateLeft((d + G(a, b, c) + this._hashValue[10] + unchecked((int)0x02441453)), S22) + a;
+            c = RotateLeft((c + G(d, a, b) + this._hashValue[15] + unchecked((int)0xd8a1e681)), S23) + d;
+            b = RotateLeft((b + G(c, d, a) + this._hashValue[4] + unchecked((int)0xe7d3fbc8)), S24) + c;
+            a = RotateLeft((a + G(b, c, d) + this._hashValue[9] + unchecked((int)0x21e1cde6)), S21) + b;
+            d = RotateLeft((d + G(a, b, c) + this._hashValue[14] + unchecked((int)0xc33707d6)), S22) + a;
+            c = RotateLeft((c + G(d, a, b) + this._hashValue[3] + unchecked((int)0xf4d50d87)), S23) + d;
+            b = RotateLeft((b + G(c, d, a) + this._hashValue[8] + unchecked((int)0x455a14ed)), S24) + c;
+            a = RotateLeft((a + G(b, c, d) + this._hashValue[13] + unchecked((int)0xa9e3e905)), S21) + b;
+            d = RotateLeft((d + G(a, b, c) + this._hashValue[2] + unchecked((int)0xfcefa3f8)), S22) + a;
+            c = RotateLeft((c + G(d, a, b) + this._hashValue[7] + unchecked((int)0x676f02d9)), S23) + d;
+            b = RotateLeft((b + G(c, d, a) + this._hashValue[12] + unchecked((int)0x8d2a4c8a)), S24) + c;
+
+            //
+            // Round 3 - H cycle, 16 times.
+            //
+            a = RotateLeft((a + H(b, c, d) + this._hashValue[5] + unchecked((int)0xfffa3942)), S31) + b;
+            d = RotateLeft((d + H(a, b, c) + this._hashValue[8] + unchecked((int)0x8771f681)), S32) + a;
+            c = RotateLeft((c + H(d, a, b) + this._hashValue[11] + unchecked((int)0x6d9d6122)), S33) + d;
+            b = RotateLeft((b + H(c, d, a) + this._hashValue[14] + unchecked((int)0xfde5380c)), S34) + c;
+            a = RotateLeft((a + H(b, c, d) + this._hashValue[1] + unchecked((int)0xa4beea44)), S31) + b;
+            d = RotateLeft((d + H(a, b, c) + this._hashValue[4] + unchecked((int)0x4bdecfa9)), S32) + a;
+            c = RotateLeft((c + H(d, a, b) + this._hashValue[7] + unchecked((int)0xf6bb4b60)), S33) + d;
+            b = RotateLeft((b + H(c, d, a) + this._hashValue[10] + unchecked((int)0xbebfbc70)), S34) + c;
+            a = RotateLeft((a + H(b, c, d) + this._hashValue[13] + unchecked((int)0x289b7ec6)), S31) + b;
+            d = RotateLeft((d + H(a, b, c) + this._hashValue[0] + unchecked((int)0xeaa127fa)), S32) + a;
+            c = RotateLeft((c + H(d, a, b) + this._hashValue[3] + unchecked((int)0xd4ef3085)), S33) + d;
+            b = RotateLeft((b + H(c, d, a) + this._hashValue[6] + unchecked((int)0x04881d05)), S34) + c;
+            a = RotateLeft((a + H(b, c, d) + this._hashValue[9] + unchecked((int)0xd9d4d039)), S31) + b;
+            d = RotateLeft((d + H(a, b, c) + this._hashValue[12] + unchecked((int)0xe6db99e5)), S32) + a;
+            c = RotateLeft((c + H(d, a, b) + this._hashValue[15] + unchecked((int)0x1fa27cf8)), S33) + d;
+            b = RotateLeft((b + H(c, d, a) + this._hashValue[2] + unchecked((int)0xc4ac5665)), S34) + c;
+
+            //
+            // Round 4 - K cycle, 16 times.
+            //
+            a = RotateLeft((a + K(b, c, d) + this._hashValue[0] + unchecked((int)0xf4292244)), S41) + b;
+            d = RotateLeft((d + K(a, b, c) + this._hashValue[7] + unchecked((int)0x432aff97)), S42) + a;
+            c = RotateLeft((c + K(d, a, b) + this._hashValue[14] + unchecked((int)0xab9423a7)), S43) + d;
+            b = RotateLeft((b + K(c, d, a) + this._hashValue[5] + unchecked((int)0xfc93a039)), S44) + c;
+            a = RotateLeft((a + K(b, c, d) + this._hashValue[12] + unchecked((int)0x655b59c3)), S41) + b;
+            d = RotateLeft((d + K(a, b, c) + this._hashValue[3] + unchecked((int)0x8f0ccc92)), S42) + a;
+            c = RotateLeft((c + K(d, a, b) + this._hashValue[10] + unchecked((int)0xffeff47d)), S43) + d;
+            b = RotateLeft((b + K(c, d, a) + this._hashValue[1] + unchecked((int)0x85845dd1)), S44) + c;
+            a = RotateLeft((a + K(b, c, d) + this._hashValue[8] + unchecked((int)0x6fa87e4f)), S41) + b;
+            d = RotateLeft((d + K(a, b, c) + this._hashValue[15] + unchecked((int)0xfe2ce6e0)), S42) + a;
+            c = RotateLeft((c + K(d, a, b) + this._hashValue[6] + unchecked((int)0xa3014314)), S43) + d;
+            b = RotateLeft((b + K(c, d, a) + this._hashValue[13] + unchecked((int)0x4e0811a1)), S44) + c;
+            a = RotateLeft((a + K(b, c, d) + this._hashValue[4] + unchecked((int)0xf7537e82)), S41) + b;
+            d = RotateLeft((d + K(a, b, c) + this._hashValue[11] + unchecked((int)0xbd3af235)), S42) + a;
+            c = RotateLeft((c + K(d, a, b) + this._hashValue[2] + unchecked((int)0x2ad7d2bb)), S43) + d;
+            b = RotateLeft((b + K(c, d, a) + this._hashValue[9] + unchecked((int)0xeb86d391)), S44) + c;
+
+            H1 += a;
+            H2 += b;
+            H3 += c;
+            H4 += d;
+
+            //
+            // reset the offset and clean out the word buffer.
+            //
+            this._offset = 0;
+            for (int i = 0; i != this._hashValue.Length; i++)
+            {
+                this._hashValue[i] = 0;
+            }
+        }
+
+    }
+}
diff --git a/Renci.SshClient/Renci.SshNet/Security/HMac.cs b/Renci.SshClient/Renci.SshNet/Security/HMac.cs
index 2b989a80..e195f078 100644
--- a/Renci.SshClient/Renci.SshNet/Security/HMac.cs
+++ b/Renci.SshClient/Renci.SshNet/Security/HMac.cs
@@ -12,7 +12,7 @@ namespace Renci.SshNet.Security
         /// <summary>
         /// Instance of initialized hash algorithm that being used
         /// </summary>
-        protected abstract HMAC Hash { get; }
+        protected abstract KeyedHashAlgorithm Hash { get; }
 
         /// <summary>
         /// Initializes algorithm with specified key.
diff --git a/Renci.SshClient/Renci.SshNet/Security/HMacMD5.cs b/Renci.SshClient/Renci.SshNet/Security/HMacMD5.cs
index 0c677832..4235fc9a 100644
--- a/Renci.SshClient/Renci.SshNet/Security/HMacMD5.cs
+++ b/Renci.SshClient/Renci.SshNet/Security/HMacMD5.cs
@@ -7,11 +7,14 @@ namespace Renci.SshNet.Security
     /// <summary>
     /// Represents MD5 implementation of hashing algorithm
     /// </summary>
-    internal class HMacMD5 : HMac
+    public class HMacMD5 : HMac
     {
-        private HMACMD5 _hash;
+        private KeyedHashAlgorithm _hash;
 
-        protected override HMAC Hash
+        /// <summary>
+        /// Instance of initialized hash algorithm that being used
+        /// </summary>
+        protected override KeyedHashAlgorithm Hash
         {
             get { return this._hash; }
         }
@@ -30,9 +33,13 @@ namespace Renci.SshNet.Security
         /// <param name="key">The hash key.</param>
         public override void Init(IEnumerable<byte> key)
         {
-            this._hash = new HMACMD5(key.Take(16).ToArray());
+            this._hash = new Renci.SshNet.Security.Cryptography.HMAC<Renci.SshNet.Security.Cryptography.MD5>(key.Take(16).ToArray());
         }
 
+        /// <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 ResourceMessages.</param>
         protected override void Dispose(bool disposing)
         {
             // Dispose managed ResourceMessages.
diff --git a/Renci.SshClient/Renci.SshNet/Security/HMacSha1.cs b/Renci.SshClient/Renci.SshNet/Security/HMacSha1.cs
index 0e932065..8bef0ef0 100644
--- a/Renci.SshClient/Renci.SshNet/Security/HMacSha1.cs
+++ b/Renci.SshClient/Renci.SshNet/Security/HMacSha1.cs
@@ -7,11 +7,14 @@ namespace Renci.SshNet.Security
     /// <summary>
     /// Represents SHA1 implementation of hashing algorithm
     /// </summary>
-    internal class HMacSha1 : HMac
+    public class HMacSha1 : HMac
     {
-        private HMACSHA1 _hash;
+        private KeyedHashAlgorithm _hash;
 
-        protected override HMAC Hash
+        /// <summary>
+        /// Instance of initialized hash algorithm that being used
+        /// </summary>
+        protected override KeyedHashAlgorithm Hash
         {
             get { return this._hash; }
         }
@@ -33,6 +36,10 @@ namespace Renci.SshNet.Security
             this._hash = new HMACSHA1(key.Take(20).ToArray());
         }
 
+        /// <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 ResourceMessages.</param>
         protected override void Dispose(bool disposing)
         {
             // Dispose managed ResourceMessages.