class/corlib/System.Security.Cryptography/AsymmetricAlgorithm.cs

   1 //
   2 // System.Security.Cryptography.AsymmetricAlgorithm 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, 2008 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
  34 namespace System.Security.Cryptography {
  35
  36         [ComVisible (true)]
  37         public abstract class AsymmetricAlgorithm : IDisposable {
  38
  39                 protected int KeySizeValue;
  40                 protected KeySizes[] LegalKeySizesValue;
  41
  42                 protected AsymmetricAlgorithm ()
  43                 {
  44                 }
  45
  46                 public abstract string KeyExchangeAlgorithm {
  47                         get;
  48                 }
  49
  50                 public virtual int KeySize {
  51                         get { return this.KeySizeValue; }
  52                         set {
  53                                 if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, value))
  54                                         throw new CryptographicException (Locale.GetText ("Key size not supported by algorithm."));
  55
  56                                 this.KeySizeValue = value;
  57                         }
  58                 }
  59
  60                 public virtual KeySizes[] LegalKeySizes {
  61                         get { return this.LegalKeySizesValue; }
  62                 }
  63
  64                 public abstract string SignatureAlgorithm {
  65                         get;
  66                 }
  67
  68                 void IDisposable.Dispose ()
  69                 {
  70                         Dispose (true);
  71                         GC.SuppressFinalize (this);  // Finalization is now unnecessary
  72                 }
  73
  74                 public void Clear ()
  75                 {
  76                         Dispose (false);
  77                 }
  78
  79                 protected abstract void Dispose (bool disposing);
  80
  81                 public abstract void FromXmlString (string xmlString);
  82
  83                 public abstract string ToXmlString (bool includePrivateParameters);
  84
  85                 public static AsymmetricAlgorithm Create ()
  86                 {
  87                         return Create ("System.Security.Cryptography.AsymmetricAlgorithm");
  88                 }
  89
  90                 public static AsymmetricAlgorithm Create (string algName)
  91                 {
  92                         return (AsymmetricAlgorithm) CryptoConfig.CreateFromName (algName);
  93                 }
  94
  95                 // parsing helper shared between DSA and RSA
  96                 internal static byte [] GetNamedParam (string xml, string param)
  97                 {
  98                         string start_element = "<" + param + ">";
  99                         int start = xml.IndexOf (start_element);
 100                         if (start == -1)
 101                                 return null;
 102
 103                         string end_element = "</" + param + ">";
 104                         int end = xml.IndexOf (end_element);
 105                         if ((end == -1) || (end <= start))
 106                                 return null;
 107
 108                         start += start_element.Length;
 109
 110                         string base64 = xml.Substring (start, end - start);
 111                         return Convert.FromBase64String (base64);
 112                 }
 113         }
 114 }