/seclib/Security/Ssl/Shared/CloneableHash.cs

/*

 *   Mentalis.org Security Library

 * 

 *     Copyright Š 2002-2005, The Mentalis.org Team

 *     All rights reserved.

 *     http://www.mentalis.org/

 *

 *

 *   Redistribution and use in source and binary forms, with or without

 *   modification, are permitted provided that the following conditions

 *   are met:

 *

 *     - Redistributions of source code must retain the above copyright

 *        notice, this list of conditions and the following disclaimer. 

 *

 *     - Neither the name of the Mentalis.org Team, nor the names of its contributors

 *        may be used to endorse or promote products derived from this

 *        software without specific prior written permission. 

 *

 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

 *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL

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 *   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

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*/



using System;

using System.Security.Cryptography;

using System.Runtime.InteropServices;

using Org.Mentalis.Security;

using Org.Mentalis.Security.Certificates;

using Org.Mentalis.Security.Cryptography;



namespace Org.Mentalis.Security.Ssl.Shared {

	internal sealed class CloneableHash : HashAlgorithm, ICloneable {

		public CloneableHash(HashType type) {

			m_Type = type;

			m_Provider = CAPIProvider.Handle;

			Initialize();

			m_Disposed = false;

		}

		public CloneableHash(int hash, HashType type, int size) {

			m_Provider = CAPIProvider.Handle;

			m_Type = type;

			m_Size = size;

			m_Disposed = false;

			if (SspiProvider.CryptDuplicateHash(hash, IntPtr.Zero, 0, out  m_Hash) == 0)

				throw new CryptographicException("Couldn't duplicate hash.");

		}

		public override void Initialize() {

			if (m_Disposed)

				throw new ObjectDisposedException(this.GetType().FullName);

			if (m_Hash != 0) {

				SspiProvider.CryptDestroyHash(m_Hash);

			}

			int type = SecurityConstants.CALG_SHA1;

			m_Size = 20;

			if (m_Type == HashType.MD5) {

				type = SecurityConstants.CALG_MD5;

				m_Size = 16;

			}

			SspiProvider.CryptCreateHash(m_Provider, type, 0, 0, out m_Hash);

		}

		protected override void HashCore(byte[] array, int ibStart, int cbSize) {

			if (ibStart > 0) {

				GCHandle handle = GCHandle.Alloc(array, GCHandleType.Pinned);

				try {

					IntPtr address = handle.AddrOfPinnedObject();

					if (SspiProvider.CryptHashData(m_Hash, new IntPtr(address.ToInt64() + ibStart), cbSize, 0) == 0)

						throw new CryptographicException("The data could not be hashed.");

				} finally {

					handle.Free();

				}

			} else {

				if (SspiProvider.CryptHashData(m_Hash, array, cbSize, 0) == 0)

					throw new CryptographicException("The data could not be hashed.");

			}

		}

		protected override byte[] HashFinal() {

			byte[] buffer = new byte[m_Size];

			int length = buffer.Length;

			if (SspiProvider.CryptGetHashParam(m_Hash, SecurityConstants.HP_HASHVAL, buffer, ref length, 0) == 0)

				throw new CryptographicException("The hash value could not be read.");

			return buffer;

		}

		public object Clone() {

			return new CloneableHash(this.m_Hash, this.m_Type, this.m_Size);

		}

		protected override void Dispose(bool disposing) {

			if (!m_Disposed) {

				if (m_Hash != 0) {

					SspiProvider.CryptDestroyHash(m_Hash);

					m_Hash = 0;

				}

				try {

					GC.SuppressFinalize(this);

				} catch {}

				m_Disposed = true;

			}

		}

		~CloneableHash() {

			Clear();

		}

		private int m_Provider;

		private int m_Hash;

		private bool m_Disposed;

		private HashType m_Type;

		private int m_Size;

	}

}