mcs/class/corlib/System.Security.Cryptography/DSA.cs

   1 //
   2 // System.Security.Cryptography.DSA.cs class implementation
   3 //
   4 // Authors:
   5 //      Thomas Neidhart (tome@sbox.tugraz.at)
   6 //      Sebastien Pouliot (sebastien@ximian.com)
   7 //
   8 // Portions (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
   9 // (C) 2004 Novell (http://www.novell.com)
  10 //
  11
  12 //
  13 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  14 //
  15 // Permission is hereby granted, free of charge, to any person obtaining
  16 // a copy of this software and associated documentation files (the
  17 // "Software"), to deal in the Software without restriction, including
  18 // without limitation the rights to use, copy, modify, merge, publish,
  19 // distribute, sublicense, and/or sell copies of the Software, and to
  20 // permit persons to whom the Software is furnished to do so, subject to
  21 // the following conditions:
  22 //
  23 // The above copyright notice and this permission notice shall be
  24 // included in all copies or substantial portions of the Software.
  25 //
  26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  33 //
  34
  35 using System;
  36 using System.Globalization;
  37 using System.Text;
  38
  39 using Mono.Xml;
  40 using Mono.Security;
  41
  42 // References:
  43 // a.   FIPS PUB 186-2: Digital Signature Standard (DSS)
  44 //      http://csrc.nist.gov/publications/fips/fips186-2/fips186-2-change1.pdf
  45
  46 namespace System.Security.Cryptography {
  47
  48         public abstract class DSA : AsymmetricAlgorithm {
  49
  50                 // LAMESPEC: It says to derive new DSA implemenation from DSA class.
  51                 // Well it's aint gonna be easy this way.
  52                 // RSA constructor is public
  53                 internal DSA ()
  54                 {
  55                 }
  56
  57                 public static new DSA Create ()
  58                 {
  59                         return Create ("System.Security.Cryptography.DSA");
  60                 }
  61
  62                 public static new DSA Create (string algName)
  63                 {
  64                         return (DSA) CryptoConfig.CreateFromName (algName);
  65                 }
  66
  67                 public abstract byte[] CreateSignature (byte[] rgbHash);
  68
  69                 public abstract DSAParameters ExportParameters (bool includePrivateParameters);
  70
  71                 internal void ZeroizePrivateKey (DSAParameters parameters)
  72                 {
  73                         if (parameters.X != null)
  74                                 Array.Clear (parameters.X, 0, parameters.X.Length);
  75                 }
  76
  77                 private byte[] GetNamedParam (SecurityElement se, string param)
  78                 {
  79                         SecurityElement sep = se.SearchForChildByTag (param);
  80                         if (sep == null)
  81                                 return null;
  82                         return Convert.FromBase64String (sep.Text);
  83                 }
  84
  85                 public override void FromXmlString (string xmlString)
  86                 {
  87                         if (xmlString == null)
  88                                 throw new ArgumentNullException ("xmlString");
  89
  90                         DSAParameters dsaParams = new DSAParameters ();
  91                         try {
  92                                 SecurityParser sp = new SecurityParser ();
  93                                 sp.LoadXml (xmlString);
  94                                 SecurityElement se = sp.ToXml ();
  95                                 if (se.Tag != "DSAKeyValue")
  96                                         throw new Exception ();
  97                                 dsaParams.P = GetNamedParam (se, "P");
  98                                 dsaParams.Q = GetNamedParam (se, "Q");
  99                                 dsaParams.G = GetNamedParam (se, "G");
 100                                 dsaParams.J = GetNamedParam (se, "J");
 101                                 dsaParams.Y = GetNamedParam (se, "Y");
 102                                 dsaParams.X = GetNamedParam (se, "X");
 103                                 dsaParams.Seed = GetNamedParam (se, "Seed");
 104                                 byte[] counter = GetNamedParam (se, "PgenCounter");
 105                                 if (counter != null) {
 106                                         byte[] counter4b = new byte [4]; // always 4 bytes
 107                                         Buffer.BlockCopy (counter, 0, counter4b, 0, counter.Length);
 108                                         dsaParams.Counter = BitConverterLE.ToInt32 (counter4b, 0);
 109                                 }
 110                                 ImportParameters (dsaParams);
 111                         }
 112                         catch {
 113                                 ZeroizePrivateKey (dsaParams);
 114                                 throw;
 115                         }
 116                         finally {
 117                                 ZeroizePrivateKey (dsaParams);
 118                         }
 119                 }
 120
 121                 public abstract void ImportParameters (DSAParameters parameters);
 122
 123                 // note: using SecurityElement.ToXml wouldn't generate the same string as the MS implementation
 124                 public override string ToXmlString (bool includePrivateParameters)
 125                 {
 126                         StringBuilder sb = new StringBuilder ();
 127                         DSAParameters dsaParams = ExportParameters (includePrivateParameters);
 128                         try {
 129                                 sb.Append ("<DSAKeyValue>");
 130
 131                                 sb.Append ("<P>");
 132                                 sb.Append (Convert.ToBase64String (dsaParams.P));
 133                                 sb.Append ("</P>");
 134
 135                                 sb.Append ("<Q>");
 136                                 sb.Append (Convert.ToBase64String (dsaParams.Q));
 137                                 sb.Append ("</Q>");
 138
 139                                 sb.Append ("<G>");
 140                                 sb.Append (Convert.ToBase64String (dsaParams.G));
 141                                 sb.Append ("</G>");
 142
 143                                 sb.Append ("<Y>");
 144                                 sb.Append (Convert.ToBase64String (dsaParams.Y));
 145                                 sb.Append( "</Y>");
 146
 147                                 sb.Append ("<J>");
 148                                 sb.Append (Convert.ToBase64String (dsaParams.J));
 149                                 sb.Append ("</J>");
 150
 151                                 if (dsaParams.Seed != null) {
 152                                         sb.Append ("<Seed>");
 153                                         sb.Append (Convert.ToBase64String (dsaParams.Seed));
 154                                         sb.Append ("</Seed>");
 155
 156                                         sb.Append ("<PgenCounter>");
 157                                         // the number of bytes is important (no matter == 0x00)
 158                                         byte[] inArr = BitConverterLE.GetBytes (dsaParams.Counter);
 159                                         int l = inArr.Length;
 160                                         while (inArr[l-1] == 0x00)
 161                                                 l--;
 162                                         byte[] c = new byte [l];
 163                                         Buffer.BlockCopy (inArr, 0, c, 0, l);
 164                                         sb.Append (Convert.ToBase64String (c));
 165                                         sb.Append ("</PgenCounter>");
 166                                 }
 167
 168                                 if (dsaParams.X != null) {
 169                                         sb.Append ("<X>");
 170                                         sb.Append (Convert.ToBase64String (dsaParams.X));
 171                                         sb.Append ("</X>");
 172                                 }
 173                                 else if (includePrivateParameters) {
 174                                         throw new CryptographicException (
 175                                                 Locale.GetText ("Missing private key informations"));
 176                                 }
 177
 178                                 sb.Append ("</DSAKeyValue>");
 179                         }
 180                         catch {
 181                                 ZeroizePrivateKey (dsaParams);
 182                                 throw;
 183                         }
 184
 185                         return sb.ToString ();
 186                 }
 187
 188                 public abstract bool VerifySignature (byte[] rgbHash, byte[] rgbSignature);
 189         }
 190 }