1 files changed, 106 insertions, 0 deletions
diff --git a/Crypto/src/crypto/tls/TlsMac.cs b/Crypto/src/crypto/tls/TlsMac.cs
new file mode 100644
index 000000000..0e58b89dc
--- /dev/null
+++ b/Crypto/src/crypto/tls/TlsMac.cs
@@ -0,0 +1,106 @@
+using System;
+using System.IO;
+
+using Org.BouncyCastle.Crypto.Digests;
+using Org.BouncyCastle.Crypto.Macs;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Tls
+{
+	/// <remarks>
+	/// A generic TLS MAC implementation, which can be used with any kind of
+	/// IDigest to act as an HMAC.
+	/// </remarks>
+	public class TlsMac
+	{
+		protected long seqNo;
+		protected byte[] secret;
+		protected HMac mac;
+
+		/**
+		* Generate a new instance of an TlsMac.
+		*
+		* @param digest    The digest to use.
+		* @param key_block A byte-array where the key for this mac is located.
+		* @param offset    The number of bytes to skip, before the key starts in the buffer.
+		* @param len       The length of the key.
+		*/
+		public TlsMac(
+			IDigest	digest,
+			byte[]	key_block,
+			int		offset,
+			int		len)
+		{
+			this.seqNo = 0;
+
+			KeyParameter param = new KeyParameter(key_block, offset, len);
+
+			this.secret = Arrays.Clone(param.GetKey());
+
+			this.mac = new HMac(digest);
+			this.mac.Init(param);
+		}
+
+		/**
+		 * @return the MAC write secret
+		 */
+		public virtual byte[] GetMacSecret()
+		{
+			return this.secret;
+		}
+
+		/**
+		 * @return the current write sequence number
+		 */
+		public virtual long SequenceNumber
+		{
+			get { return this.seqNo; }
+		}
+
+		/**
+		 * Increment the current write sequence number
+		 */
+		public virtual void IncSequenceNumber()
+		{
+			this.seqNo++;
+		}
+
+		/**
+		* @return The Keysize of the mac.
+		*/
+		public virtual int Size
+		{
+			get { return mac.GetMacSize(); }
+		}
+
+		/**
+		* Calculate the mac for some given data.
+		* <p/>
+		* TlsMac will keep track of the sequence number internally.
+		*
+		* @param type    The message type of the message.
+		* @param message A byte-buffer containing the message.
+		* @param offset  The number of bytes to skip, before the message starts.
+		* @param len     The length of the message.
+		* @return A new byte-buffer containing the mac value.
+		*/
+		public virtual byte[] CalculateMac(
+			ContentType	type,
+			byte[]		message,
+			int			offset,
+			int			len)
+		{
+			byte[] macHeader = new byte[13];
+			TlsUtilities.WriteUint64(seqNo++, macHeader, 0);
+			TlsUtilities.WriteUint8((byte)type, macHeader, 8);
+			TlsUtilities.WriteVersion(macHeader, 9);
+			TlsUtilities.WriteUint16(len, macHeader, 11);
+
+			mac.BlockUpdate(macHeader, 0, macHeader.Length);
+			mac.BlockUpdate(message, offset, len);
+			return MacUtilities.DoFinal(mac);
+		}
+	}
+}