/* 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 SX509 = System.Security.Cryptography.X509Certificates;

using Mono.Security.Cryptography;
using Mono.Security.X509;

namespace Mono.Security.Protocol.Tls.Handshake.Server
{
	internal class TlsServerKeyExchange : HandshakeMessage
	{
		#region Constructors

		public TlsServerKeyExchange(Context context)
			: base(context, HandshakeType.ServerKeyExchange)
		{
		}

		#endregion

		#region Methods

		public override void Update()
		{
			throw new NotSupportedException();
		}

		#endregion

		#region Protected Methods

		protected override void ProcessAsSsl3()
		{
			this.ProcessAsTls1();
		}

		protected override void ProcessAsTls1()
		{
			ServerContext context = (ServerContext)this.Context;

			// Select the private key information
			RSA rsa = (RSA)context.SslStream.PrivateKeyCertSelectionDelegate(
				new SX509.X509Certificate(context.ServerSettings.Certificates[0].RawData),
				null);

			RSAParameters rsaParams = rsa.ExportParameters(false);

			// Write Modulus
			this.WriteInt24(rsaParams.Modulus.Length);
			this.Write(rsaParams.Modulus, 0, rsaParams.Modulus.Length);
			
			// Write exponent
			this.WriteInt24(rsaParams.Exponent.Length);
			this.Write(rsaParams.Exponent, 0, rsaParams.Exponent.Length);

			// Write signed params
			byte[] signature = this.createSignature(rsa, this.ToArray());
			this.WriteInt24(signature.Length);
			this.Write(signature);
		}

		#endregion

		#region Private Methods

		private byte[] createSignature(RSA rsa, byte[] buffer)
		{
			MD5SHA1	hash = new MD5SHA1();

			// Create server params array
			TlsStream stream = new TlsStream();

			stream.Write(this.Context.RandomCS);
			stream.Write(buffer, 0, buffer.Length);

			hash.ComputeHash(stream.ToArray());

			stream.Reset();

			return hash.CreateSignature(rsa);			
		}

		#endregion
	}
}