Initial Commit

iTechSharp/srcbc/cms/CMSEnvelopedHelper.cs

@@ -0,0 +1,99 @@
+using System;
+using System.Collections;
+
+using Org.BouncyCastle.Asn1.Pkcs;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Security;
+
+namespace Org.BouncyCastle.Cms
+{
+	class CmsEnvelopedHelper
+	{
+		internal static readonly CmsEnvelopedHelper Instance = new CmsEnvelopedHelper();
+
+		private static readonly IDictionary KeySizes = new Hashtable();
+		private static readonly IDictionary Ciphers = new Hashtable();
+		private static readonly IDictionary BaseCipherNames = new Hashtable();
+//		private static readonly IDictionary CipherAlgNames = new Hashtable();
+
+		static CmsEnvelopedHelper()
+		{
+			KeySizes.Add(CmsEnvelopedGenerator.DesEde3Cbc, 192);
+			KeySizes.Add(CmsEnvelopedGenerator.Aes128Cbc, 128);
+			KeySizes.Add(CmsEnvelopedGenerator.Aes192Cbc, 192);
+			KeySizes.Add(CmsEnvelopedGenerator.Aes256Cbc, 256);
+
+			BaseCipherNames.Add(CmsEnvelopedGenerator.DesEde3Cbc,  "DESEDE");
+			BaseCipherNames.Add(CmsEnvelopedGenerator.Aes128Cbc,  "AES");
+			BaseCipherNames.Add(CmsEnvelopedGenerator.Aes192Cbc,  "AES");
+			BaseCipherNames.Add(CmsEnvelopedGenerator.Aes256Cbc,  "AES");
+
+//			CipherAlgNames.Add(CmsEnvelopedGenerator.DesEde3Cbc,  "DESEDE/CBC/PKCS5Padding");
+//			CipherAlgNames.Add(CmsEnvelopedGenerator.Aes128Cbc,  "AES/CBC/PKCS5Padding");
+//			CipherAlgNames.Add(CmsEnvelopedGenerator.Aes192Cbc,  "AES/CBC/PKCS5Padding");
+//			CipherAlgNames.Add(CmsEnvelopedGenerator.Aes256Cbc,  "AES/CBC/PKCS5Padding");
+		}
+
+		private string GetAsymmetricEncryptionAlgName(
+			string encryptionAlgOid)
+		{
+			if (PkcsObjectIdentifiers.RsaEncryption.Id.Equals(encryptionAlgOid))
+			{
+				return "RSA/ECB/PKCS1Padding";
+			}
+
+			return encryptionAlgOid;    
+		}
+
+		internal IBufferedCipher CreateAsymmetricCipher(
+			string encryptionOid)
+		{
+			try
+			{
+				return CipherUtilities.GetCipher(encryptionOid);
+			}
+			catch (SecurityUtilityException)
+			{
+				return CipherUtilities.GetCipher(GetAsymmetricEncryptionAlgName(encryptionOid));
+			}
+		}
+
+		internal IWrapper CreateWrapper(
+			string encryptionOid)
+		{
+			try
+			{
+				return WrapperUtilities.GetWrapper(encryptionOid);
+			}
+			catch (SecurityUtilityException)
+			{
+				return WrapperUtilities.GetWrapper(GetAsymmetricEncryptionAlgName(encryptionOid));
+			}
+		}
+
+		internal string GetRfc3211WrapperName(
+			string oid)
+		{
+			if (oid == null)
+				throw new ArgumentNullException("oid");
+
+			string alg = (string) BaseCipherNames[oid];
+
+			if (alg == null)
+				throw new ArgumentException("no name for " + oid, "oid");
+
+			return alg + "RFC3211Wrap";
+		}
+
+		internal int GetKeySize(
+			string oid)
+		{
+			if (!KeySizes.Contains(oid))
+			{
+				throw new ArgumentException("no keysize for " + oid, "oid");
+			}
+
+			return (int) KeySizes[oid];
+		}
+	}
+}