Fixed RC2 algorithm mapping for S/MIME

Thanks to Alexander Bauer for this patch. Fixes issue #337
jstedfast · Sep 12, 2017 · 794288f · 794288f
1 parent 0478738
commit 794288f
Showing 1 changed file with 6 additions and 5 deletions.
diff --git a/MimeKit/Cryptography/SecureMimeContext.cs b/MimeKit/Cryptography/SecureMimeContext.cs
@@ -833,13 +833,14 @@ internal protected static bool TryGetEncryptionAlgorithm (AlgorithmIdentifier id
 			}
 
 			if (identifier.Algorithm.Id == CmsEnvelopedGenerator.RC2Cbc) {
-				var param = (DerInteger) identifier.Parameters;
-				int bits = param.Value.IntValue;
+				var param = (DerSequence) identifier.Parameters;
+				var version = (DerInteger) param[0];
+				int bits = version.Value.IntValue;
 
 				switch (bits) {
-				case 128: algorithm = EncryptionAlgorithm.RC2128; return true;
-				case 64: algorithm = EncryptionAlgorithm.RC264; return true;
-				case 40: algorithm = EncryptionAlgorithm.RC240; return true;
+				case 58: algorithm = EncryptionAlgorithm.RC2128; return true;
+				case 120: algorithm = EncryptionAlgorithm.RC264; return true;
+				case 160: algorithm = EncryptionAlgorithm.RC240; return true;
 				}
 			}