Initial Commit

iTechSharp/srcbc/cms/KeyAgreeRecipientInformation.cs

@@ -0,0 +1,122 @@
+using System;
+using System.IO;
+
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.Cms;
+using Org.BouncyCastle.Asn1.Pkcs;
+using Org.BouncyCastle.Asn1.X509;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Pkcs;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.X509;
+
+namespace Org.BouncyCastle.Cms
+{
+	/**
+	* the RecipientInfo class for a recipient who has been sent a message
+	* encrypted using key agreement.
+	*/
+	public class KeyAgreeRecipientInformation
+		: RecipientInformation
+	{
+		private KeyAgreeRecipientInfo _info;
+//		private AlgorithmIdentifier   _encAlg;
+		private Asn1OctetString       _encryptedKey;
+
+		public KeyAgreeRecipientInformation(
+			KeyAgreeRecipientInfo	info,
+			AlgorithmIdentifier		encAlg,
+			Stream					data)
+			: base(encAlg, AlgorithmIdentifier.GetInstance(info.KeyEncryptionAlgorithm), data)
+		{
+			_info = info;
+//			_encAlg = encAlg;
+
+			try
+			{
+				Asn1Sequence s = _info.RecipientEncryptedKeys;
+				RecipientEncryptedKey id = RecipientEncryptedKey.GetInstance(s[0]);
+
+				Asn1.Cms.IssuerAndSerialNumber iAnds = id.Identifier.IssuerAndSerialNumber;
+
+//				byte[] issuerBytes = iAnds.Name.GetEncoded();
+
+				_rid = new RecipientID();
+//				_rid.SetIssuer(issuerBytes);
+				_rid.Issuer = iAnds.Name;
+				_rid.SerialNumber = iAnds.SerialNumber.Value;
+
+				_encryptedKey = id.EncryptedKey;
+			}
+			catch (IOException e)
+			{
+				throw new ArgumentException("invalid rid in KeyAgreeRecipientInformation", e);
+			}
+		}
+
+		/**
+		* decrypt the content and return an input stream.
+		*/
+		public override CmsTypedStream GetContentStream(
+//			Key key)
+			ICipherParameters key)
+		{
+			if (!(key is AsymmetricKeyParameter))
+				throw new ArgumentException("KeyAgreement requires asymmetric key", "key");
+
+			AsymmetricKeyParameter privKey = (AsymmetricKeyParameter) key;
+
+			if (!privKey.IsPrivate)
+				throw new ArgumentException("Expected private key", "key");
+
+			try
+			{
+				OriginatorPublicKey origK = _info.Originator.OriginatorKey;
+				PrivateKeyInfo privInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(privKey);
+				SubjectPublicKeyInfo pubInfo = new SubjectPublicKeyInfo(privInfo.AlgorithmID, origK.PublicKey.GetBytes());
+				AsymmetricKeyParameter pubKey = PublicKeyFactory.CreateKey(pubInfo);
+
+				string wrapAlg = DerObjectIdentifier.GetInstance(
+					Asn1Sequence.GetInstance(_keyEncAlg.Parameters)[0]).Id;
+
+				IBasicAgreement agreement = AgreementUtilities.GetBasicAgreementWithKdf(
+					_keyEncAlg.ObjectID, wrapAlg);
+
+				agreement.Init(privKey);
+
+				BigInteger wKeyNum = agreement.CalculateAgreement(pubKey);
+				// TODO Fix the way bytes are derived from the secret
+				byte[] wKeyBytes = wKeyNum.ToByteArrayUnsigned();
+				KeyParameter wKey = ParameterUtilities.CreateKeyParameter(wrapAlg, wKeyBytes);
+
+				IWrapper keyCipher = WrapperUtilities.GetWrapper(wrapAlg);
+
+				keyCipher.Init(false, wKey);
+
+				AlgorithmIdentifier aid = _encAlg;
+				string alg = aid.ObjectID.Id;
+
+				byte[] encryptedKey = _encryptedKey.GetOctets();
+				byte[] sKeyBytes = keyCipher.Unwrap(encryptedKey, 0, encryptedKey.Length);
+
+				KeyParameter sKey = ParameterUtilities.CreateKeyParameter(alg, sKeyBytes);
+
+				return GetContentFromSessionKey(sKey);
+			}
+			catch (SecurityUtilityException e)
+			{
+				throw new CmsException("couldn't create cipher.", e);
+			}
+			catch (InvalidKeyException e)
+			{
+				throw new CmsException("key invalid in message.", e);
+			}
+			catch (Exception e)
+			{
+				throw new CmsException("originator key invalid.", e);
+			}
+		}
+	}
+}