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//
// HMAC.cs: Generic HMAC inplementation
//
// Author:
// Sebastien Pouliot <sebastien@ximian.com>
//
// (C) 2003 Motus Technologies Inc. (http://www.motus.com)
// Copyright (C) 2004-2005, 2007 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
#if NET_2_0
using System.Runtime.InteropServices;
using Mono.Security.Cryptography;
namespace System.Security.Cryptography {
// Mostly copied from (internal) Mono.Security.Cryptography.HMACAlgorithm
// References:
// a. FIPS PUB 198: The Keyed-Hash Message Authentication Code (HMAC), 2002 March.
// http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf
// b. Internet RFC 2104, HMAC, Keyed-Hashing for Message Authentication
// (include C source for HMAC-MD5)
// http://www.ietf.org/rfc/rfc2104.txt
// c. IETF RFC2202: Test Cases for HMAC-MD5 and HMAC-SHA-1
// (include C source for HMAC-MD5 and HAMAC-SHA1)
// http://www.ietf.org/rfc/rfc2202.txt
// d. ANSI X9.71, Keyed Hash Message Authentication Code.
// not free :-(
// http://webstore.ansi.org/ansidocstore/product.asp?sku=ANSI+X9%2E71%2D2000
[ComVisible (true)]
public abstract class HMAC : KeyedHashAlgorithm {
private bool _disposed;
private string _hashName;
private HashAlgorithm _algo;
private BlockProcessor _block;
private int _blockSizeValue;
// constructors
protected HMAC ()
{
_disposed = false;
_blockSizeValue = 64;
}
// properties
protected int BlockSizeValue {
get { return _blockSizeValue; }
set { _blockSizeValue = value; }
}
public string HashName {
get { return _hashName; }
set {
_hashName = value;
_algo = HashAlgorithm.Create (_hashName);
}
}
public override byte[] Key {
get { return (byte[]) base.Key.Clone (); }
set {
if ((value != null) && (value.Length > 64))
base.Key = _algo.ComputeHash (value);
else
base.Key = (byte[]) value.Clone();
}
}
internal BlockProcessor Block {
get {
if (_block == null)
_block = new BlockProcessor (_algo, (BlockSizeValue >> 3));
return _block;
}
}
// methods
private byte[] KeySetup (byte[] key, byte padding)
{
byte[] buf = new byte [BlockSizeValue];
for (int i = 0; i < key.Length; ++i)
buf [i] = (byte) ((byte) key [i] ^ padding);
for (int i = key.Length; i < BlockSizeValue; ++i)
buf [i] = padding;
return buf;
}
protected override void Dispose (bool disposing)
{
if (!_disposed) {
base.Dispose (disposing);
}
}
protected override void HashCore (byte[] rgb, int ib, int cb)
{
if (_disposed)
throw new ObjectDisposedException ("HMACSHA1");
if (State == 0) {
Initialize ();
State = 1;
}
Block.Core (rgb, ib, cb);
}
protected override byte[] HashFinal ()
{
if (_disposed)
throw new ObjectDisposedException ("HMAC");
State = 0;
Block.Final ();
byte[] intermediate = _algo.Hash;
byte[] buf = KeySetup (Key, 0x5C);
_algo.Initialize ();
_algo.TransformBlock (buf, 0, buf.Length, buf, 0);
_algo.TransformFinalBlock (intermediate, 0, intermediate.Length);
byte[] hash = _algo.Hash;
_algo.Initialize ();
// zeroize sensitive data
Array.Clear (buf, 0, buf.Length);
Array.Clear (intermediate, 0, intermediate.Length);
return hash;
}
public override void Initialize ()
{
if (_disposed)
throw new ObjectDisposedException ("HMAC");
State = 0;
Block.Initialize ();
byte[] buf = KeySetup (Key, 0x36);
_algo.Initialize ();
Block.Core (buf);
// zeroize key
Array.Clear (buf, 0, buf.Length);
}
// static methods
public static new HMAC Create ()
{
return Create ("System.Security.Cryptography.HMAC");
}
public static new HMAC Create (string algorithmName)
{
return (HMAC) CryptoConfig.CreateFromName (algorithmName);
}
}
}
#endif
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