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 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System.Globalization;
  32 using System.Runtime.InteropServices;
  33 using System.Text;
  34
  35 using Mono.Xml;
  36 using Mono.Security;
  37
  38 // References:
  39 // a.   FIPS PUB 186-2: Digital Signature Standard (DSS)
  40 //      http://csrc.nist.gov/publications/fips/fips186-2/fips186-2-change1.pdf
  41
  42 namespace System.Security.Cryptography {
  43
  44 #if NET_2_0
  45         [ComVisible (true)]
  46 #endif
  47         public abstract class DSA : AsymmetricAlgorithm {
  48
  49 #if NET_2_0
  50                 // Constructor visibility fixed in Fx 2.0
  51                 protected DSA ()
  52 #else
  53                 // LAMESPEC: It says to derive new DSA implemenation from DSA class.
  54                 // Well it's aint gonna be easy this way.
  55                 // RSA constructor is public
  56                 internal DSA ()
  57 #endif
  58                 {
  59                 }
  60
  61                 public static new DSA Create ()
  62                 {
  63                         return Create ("System.Security.Cryptography.DSA");
  64                 }
  65
  66                 public static new DSA Create (string algName)
  67                 {
  68                         return (DSA) CryptoConfig.CreateFromName (algName);
  69                 }
  70
  71                 public abstract byte[] CreateSignature (byte[] rgbHash);
  72
  73                 public abstract DSAParameters ExportParameters (bool includePrivateParameters);
  74
  75                 internal void ZeroizePrivateKey (DSAParameters parameters)
  76                 {
  77                         if (parameters.X != null)
  78                                 Array.Clear (parameters.X, 0, parameters.X.Length);
  79                 }
  80
  81                 private byte[] GetNamedParam (SecurityElement se, string param)
  82                 {
  83                         SecurityElement sep = se.SearchForChildByTag (param);
  84                         if (sep == null)
  85                                 return null;
  86                         return Convert.FromBase64String (sep.Text);
  87                 }
  88
  89                 public override void FromXmlString (string xmlString)
  90                 {
  91                         if (xmlString == null)
  92                                 throw new ArgumentNullException ("xmlString");
  93
  94                         DSAParameters dsaParams = new DSAParameters ();
  95                         try {
  96                                 SecurityParser sp = new SecurityParser ();
  97                                 sp.LoadXml (xmlString);
  98                                 SecurityElement se = sp.ToXml ();
  99                                 if (se.Tag != "DSAKeyValue")
 100                                         throw new Exception ();
 101                                 dsaParams.P = GetNamedParam (se, "P");
 102                                 dsaParams.Q = GetNamedParam (se, "Q");
 103                                 dsaParams.G = GetNamedParam (se, "G");
 104                                 dsaParams.J = GetNamedParam (se, "J");
 105                                 dsaParams.Y = GetNamedParam (se, "Y");
 106                                 dsaParams.X = GetNamedParam (se, "X");
 107                                 dsaParams.Seed = GetNamedParam (se, "Seed");
 108                                 byte[] counter = GetNamedParam (se, "PgenCounter");
 109                                 if (counter != null) {
 110                                         byte[] counter4b = new byte [4]; // always 4 bytes
 111                                         Buffer.BlockCopy (counter, 0, counter4b, 0, counter.Length);
 112                                         dsaParams.Counter = BitConverterLE.ToInt32 (counter4b, 0);
 113                                 }
 114                                 ImportParameters (dsaParams);
 115                         }
 116                         catch {
 117                                 ZeroizePrivateKey (dsaParams);
 118                                 throw;
 119                         }
 120                         finally {
 121                                 ZeroizePrivateKey (dsaParams);
 122                         }
 123                 }
 124
 125                 public abstract void ImportParameters (DSAParameters parameters);
 126
 127                 // note: using SecurityElement.ToXml wouldn't generate the same string as the MS implementation
 128                 public override string ToXmlString (bool includePrivateParameters)
 129                 {
 130                         StringBuilder sb = new StringBuilder ();
 131                         DSAParameters dsaParams = ExportParameters (includePrivateParameters);
 132                         try {
 133                                 sb.Append ("<DSAKeyValue>");
 134
 135                                 sb.Append ("<P>");
 136                                 sb.Append (Convert.ToBase64String (dsaParams.P));
 137                                 sb.Append ("</P>");
 138
 139                                 sb.Append ("<Q>");
 140                                 sb.Append (Convert.ToBase64String (dsaParams.Q));
 141                                 sb.Append ("</Q>");
 142
 143                                 sb.Append ("<G>");
 144                                 sb.Append (Convert.ToBase64String (dsaParams.G));
 145                                 sb.Append ("</G>");
 146
 147                                 sb.Append ("<Y>");
 148                                 sb.Append (Convert.ToBase64String (dsaParams.Y));
 149                                 sb.Append( "</Y>");
 150
 151                                 if (dsaParams.J != null) {
 152                                         // if J wasn't imported then it's not exported and neither
 153                                         // is part of the XML output
 154                                         sb.Append ("<J>");
 155                                         sb.Append (Convert.ToBase64String (dsaParams.J));
 156                                         sb.Append ("</J>");
 157                                 }
 158
 159                                 if (dsaParams.Seed != null) {
 160                                         sb.Append ("<Seed>");
 161                                         sb.Append (Convert.ToBase64String (dsaParams.Seed));
 162                                         sb.Append ("</Seed>");
 163
 164                                         sb.Append ("<PgenCounter>");
 165                                         // the number of bytes is important (no matter == 0x00)
 166                                         if (dsaParams.Counter != 0) {
 167                                                 byte[] inArr = BitConverterLE.GetBytes (dsaParams.Counter);
 168                                                 int l = inArr.Length;
 169                                                 while (inArr[l-1] == 0x00)
 170                                                         l--;
 171
 172                                                 sb.Append (Convert.ToBase64String (inArr, 0, l));
 173                                         } else {
 174                                                 sb.Append ("AA==");     // base64 encoded 0
 175                                         }
 176                                         sb.Append ("</PgenCounter>");
 177                                 }
 178
 179                                 if (dsaParams.X != null) {
 180                                         sb.Append ("<X>");
 181                                         sb.Append (Convert.ToBase64String (dsaParams.X));
 182                                         sb.Append ("</X>");
 183                                 }
 184                                 else if (includePrivateParameters) {
 185 #if NET_2_0
 186                                         throw new ArgumentNullException ("X");
 187 #else
 188                                         throw new CryptographicException (
 189                                                 Locale.GetText ("Missing private key informations"));
 190 #endif
 191                                 }
 192
 193                                 sb.Append ("</DSAKeyValue>");
 194                         }
 195                         catch {
 196                                 ZeroizePrivateKey (dsaParams);
 197                                 throw;
 198                         }
 199
 200                         return sb.ToString ();
 201                 }
 202
 203                 public abstract bool VerifySignature (byte[] rgbHash, byte[] rgbSignature);
 204         }
 205 }