/* Transport Security Layer (TLS)
 * Copyright (c) 2003-2004 Carlos Guzman Alvarez
 * 
 * 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;
using System.Security.Cryptography;

using Mono.Security.Protocol.Tls;

namespace Mono.Security.Cryptography
{
	internal class MD5SHA1 : HashAlgorithm
	{
		#region Fields

		private HashAlgorithm	md5;
		private HashAlgorithm	sha;
		private bool			hashing;

		#endregion

		#region Constructors

		public MD5SHA1() : base()
		{
			this.md5 = MD5.Create();
			this.sha = SHA1.Create();

			// Set HashSizeValue
			this.HashSizeValue = this.md5.HashSize + this.sha.HashSize;
		}

		#endregion

		#region Methods

		public override void Initialize()
		{
			this.md5.Initialize();
			this.sha.Initialize();
			this.hashing = false;
		}

		protected override byte[] HashFinal()
		{
			if (!hashing)
			{
				this.hashing = true;
			}
			// Finalize the original hash
			this.md5.TransformFinalBlock(new byte[0], 0, 0);
			this.sha.TransformFinalBlock(new byte[0], 0, 0);

			byte[] hash = new byte[36];

			Buffer.BlockCopy(this.md5.Hash, 0, hash, 0, 16);
			Buffer.BlockCopy(this.sha.Hash, 0, hash, 16, 20);

			return hash;
		}

		protected override void HashCore(
			byte[] array,
			int ibStart,
			int cbSize)
		{
			if (!hashing)
			{
				hashing = true;
			}
			this.md5.TransformBlock(array, ibStart, cbSize, array, ibStart);
			this.sha.TransformBlock(array, ibStart, cbSize, array, ibStart);
		}

		public byte[] CreateSignature(RSA rsa) 
		{
			if (rsa == null)
			{
				throw new CryptographicUnexpectedOperationException ("missing key");
			}

			RSASslSignatureFormatter f = new RSASslSignatureFormatter(rsa);
			f.SetHashAlgorithm("MD5SHA1");

			return f.CreateSignature(this.Hash);
		}

		public bool VerifySignature(RSA rsa, byte[] rgbSignature) 
		{
			if (rsa == null)
			{
				throw new CryptographicUnexpectedOperationException ("missing key");
			}
			if (rgbSignature == null)
			{
				throw new ArgumentNullException ("rgbSignature");
			}

			RSASslSignatureDeformatter d = new RSASslSignatureDeformatter(rsa);
			d.SetHashAlgorithm("MD5SHA1");

			return d.VerifySignature(this.Hash, rgbSignature);
		}

		#endregion
	}
}