class/Mono.Security/Mono.Security.Protocol.Tls.Handshake.Client/TlsServerKeyExchange.cs

   1 // Transport Security Layer (TLS)
   2 // Copyright (c) 2003-2004 Carlos Guzman Alvarez
   3
   4 //
   5 // Permission is hereby granted, free of charge, to any person obtaining
   6 // a copy of this software and associated documentation files (the
   7 // "Software"), to deal in the Software without restriction, including
   8 // without limitation the rights to use, copy, modify, merge, publish,
   9 // distribute, sublicense, and/or sell copies of the Software, and to
  10 // permit persons to whom the Software is furnished to do so, subject to
  11 // the following conditions:
  12 //
  13 // The above copyright notice and this permission notice shall be
  14 // included in all copies or substantial portions of the Software.
  15 //
  16 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  17 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  18 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  19 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  20 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  21 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  22 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23 //
  24
  25 using System;
  26 using System.Security.Cryptography;
  27
  28 using Mono.Security.Cryptography;
  29 using Mono.Security.X509;
  30
  31 namespace Mono.Security.Protocol.Tls.Handshake.Client
  32 {
  33         internal class TlsServerKeyExchange : HandshakeMessage
  34         {
  35                 #region Fields
  36
  37                 private RSAParameters   rsaParams;
  38                 private byte[]                  signedParams;
  39
  40                 #endregion
  41
  42                 #region Constructors
  43
  44                 public TlsServerKeyExchange(Context context, byte[] buffer)
  45                         : base(context, HandshakeType.ServerKeyExchange, buffer)
  46                 {
  47                         this.verifySignature();
  48                 }
  49
  50                 #endregion
  51
  52                 #region Methods
  53
  54                 public override void Update()
  55                 {
  56                         base.Update();
  57
  58                         this.Context.ServerSettings.ServerKeyExchange   = true;
  59                         this.Context.ServerSettings.RsaParameters               = this.rsaParams;
  60                         this.Context.ServerSettings.SignedParams                = this.signedParams;
  61                 }
  62
  63                 #endregion
  64
  65                 #region Protected Methods
  66
  67                 protected override void ProcessAsSsl3()
  68                 {
  69                         this.ProcessAsTls1();
  70                 }
  71
  72                 protected override void ProcessAsTls1()
  73                 {
  74                         this.rsaParams = new RSAParameters();
  75
  76                         // Read modulus
  77                         this.rsaParams.Modulus  = this.ReadBytes(this.ReadInt16());
  78
  79                         // Read exponent
  80                         this.rsaParams.Exponent = this.ReadBytes(this.ReadInt16());
  81
  82                         // Read signed params
  83                         this.signedParams               = this.ReadBytes(this.ReadInt16());
  84                 }
  85
  86                 #endregion
  87
  88                 #region Private Methods
  89
  90                 private void verifySignature()
  91                 {
  92                         MD5SHA1 hash = new MD5SHA1();
  93
  94                         // Calculate size of server params
  95                         int size = rsaParams.Modulus.Length + rsaParams.Exponent.Length + 4;
  96
  97                         // Create server params array
  98                         TlsStream stream = new TlsStream();
  99
 100                         stream.Write(this.Context.RandomCS);
 101                         stream.Write(this.ToArray(), 0, size);
 102
 103                         hash.ComputeHash(stream.ToArray());
 104
 105                         stream.Reset();
 106
 107                         bool isValidSignature = hash.VerifySignature(
 108                                 this.Context.ServerSettings.CertificateRSA,
 109                                 this.signedParams);
 110
 111                         if (!isValidSignature)
 112                         {
 113                                 throw new TlsException(
 114                                         AlertDescription.DecodeError,
 115                                         "Data was not signed with the server certificate.");
 116                         }
 117                 }
 118
 119                 #endregion
 120         }
 121 }