//
// KeyedHashAlgorithm.cs: Handles keyed hash and MAC classes.
//
// Author:
// Sebastien Pouliot (sebastien@ximian.com)
//
// (C) 2002 Motus Technologies Inc. (http://www.motus.com)
// Copyright (C) 2004-2005 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.
//
using System.Globalization;
using System.Runtime.InteropServices;
namespace System.Security.Cryptography{
[ComVisible (true)]
public abstract class KeyedHashAlgorithm : HashAlgorithm {
protected byte[] KeyValue;
protected KeyedHashAlgorithm () : base ()
{
// create a random 64 bits key
}
~KeyedHashAlgorithm ()
{
Dispose (false);
}
public virtual byte[] Key {
get {
return (byte[]) KeyValue.Clone ();
}
set {
// can't change the key during a hashing ops
if (State != 0) {
throw new CryptographicException (
Locale.GetText ("Key can't be changed at this state."));
}
// zeroize current key material for security
ZeroizeKey ();
// copy new key
KeyValue = (byte[]) value.Clone ();
}
}
protected override void Dispose (bool disposing)
{
// zeroize key material for security
ZeroizeKey();
// dispose managed resources
// none so far
// dispose unmanaged resources
// none so far
// calling base class HashAlgorithm
base.Dispose (disposing);
}
private void ZeroizeKey()
{
if (KeyValue != null)
Array.Clear (KeyValue, 0, KeyValue.Length);
}
public static new KeyedHashAlgorithm Create ()
{
return Create ("System.Security.Cryptography.KeyedHashAlgorithm");
}
public static new KeyedHashAlgorithm Create (string algName)
{
return (KeyedHashAlgorithm) CryptoConfig.CreateFromName (algName);
}
}
}
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