mcs/class/referencesource/mscorlib/system/security/cryptography/dsasignatureformatter.cs

   1 // ==++==
   2 //
   3 //   Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //
   5 // ==--==
   6 // <OWNER>Microsoft</OWNER>
   7 //
   8
   9 //
  10 // DSASignatureFormatter.cs
  11 //
  12
  13 using System;
  14 using System.Diagnostics.Contracts;
  15 using System.Security.Cryptography.X509Certificates;
  16
  17 namespace System.Security.Cryptography {
  18     [System.Runtime.InteropServices.ComVisible(true)]
  19     public class DSASignatureFormatter : AsymmetricSignatureFormatter {
  20         DSA    _dsaKey;
  21         String _oid;
  22
  23         //
  24         // public constructors
  25         //
  26
  27         public DSASignatureFormatter() {
  28             // The hash algorithm is always SHA1
  29             _oid = CryptoConfig.MapNameToOID("SHA1", OidGroup.HashAlgorithm);
  30         }
  31
  32         public DSASignatureFormatter(AsymmetricAlgorithm key) : this() {
  33             if (key == null)
  34                 throw new ArgumentNullException("key");
  35             Contract.EndContractBlock();
  36             _dsaKey = (DSA) key;
  37         }
  38
  39         //
  40         // public methods
  41         //
  42
  43         public override void SetKey(AsymmetricAlgorithm key) {
  44             if (key == null)
  45                 throw new ArgumentNullException("key");
  46             Contract.EndContractBlock();
  47             _dsaKey = (DSA) key;
  48         }
  49
  50         public override void SetHashAlgorithm(String strName) {
  51             if (CryptoConfig.MapNameToOID(strName, OidGroup.HashAlgorithm) != _oid)
  52                 throw new CryptographicUnexpectedOperationException(Environment.GetResourceString("Cryptography_InvalidOperation"));
  53         }
  54
  55         public override byte[] CreateSignature(byte[] rgbHash) {
  56             if (rgbHash == null)
  57                 throw new ArgumentNullException("rgbHash");
  58             Contract.EndContractBlock();
  59
  60             if (_oid == null)
  61                 throw new CryptographicUnexpectedOperationException(Environment.GetResourceString("Cryptography_MissingOID"));
  62             if (_dsaKey == null)
  63                 throw new CryptographicUnexpectedOperationException(Environment.GetResourceString("Cryptography_MissingKey"));
  64
  65             return _dsaKey.CreateSignature(rgbHash);
  66         }
  67     }
  68 }