Initial Commit

iTechSharp/srcbc/crypto/agreement/ECDHWithKdfBasicAgreement.cs

@@ -0,0 +1,68 @@
+using System;
+using System.Collections;
+
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.Nist;
+using Org.BouncyCastle.Asn1.Pkcs;
+using Org.BouncyCastle.Crypto.Agreement.Kdf;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+
+namespace Org.BouncyCastle.Crypto.Agreement
+{
+	public class ECDHWithKdfBasicAgreement
+		: ECDHBasicAgreement
+	{
+		private static readonly Hashtable algorithms = new Hashtable();
+
+		static ECDHWithKdfBasicAgreement()
+		{
+			algorithms.Add(NistObjectIdentifiers.IdAes128Cbc.Id, 128);
+			algorithms.Add(NistObjectIdentifiers.IdAes192Cbc.Id, 192);
+			algorithms.Add(NistObjectIdentifiers.IdAes256Cbc.Id, 256);
+			algorithms.Add(NistObjectIdentifiers.IdAes128Wrap.Id, 128);
+			algorithms.Add(NistObjectIdentifiers.IdAes192Wrap.Id, 192);
+			algorithms.Add(NistObjectIdentifiers.IdAes256Wrap.Id, 256);
+			algorithms.Add(PkcsObjectIdentifiers.IdAlgCms3DesWrap.Id, 192);
+		}
+
+		private readonly string algorithm;
+		private readonly IDerivationFunction kdf;
+
+		public ECDHWithKdfBasicAgreement(
+			string				algorithm,
+			IDerivationFunction	kdf)
+		{
+			if (algorithm == null)
+				throw new ArgumentNullException("algorithm");
+			if (!algorithms.Contains(algorithm))
+				throw new ArgumentException("Unknown algorithm", "algorithm");
+			if (kdf == null)
+				throw new ArgumentNullException("kdf");
+
+			this.algorithm = algorithm;
+			this.kdf = kdf;
+		}
+
+		public override BigInteger CalculateAgreement(
+			ICipherParameters pubKey)
+		{
+			BigInteger result = base.CalculateAgreement(pubKey);
+
+			int keySize = (int) algorithms[algorithm];
+
+			DHKdfParameters dhKdfParams = new DHKdfParameters(
+				new DerObjectIdentifier(algorithm),
+				keySize,
+				// TODO Fix the way bytes are derived from the secret
+				result.ToByteArrayUnsigned());
+
+			kdf.Init(dhKdfParams);
+
+			byte[] keyBytes = new byte[keySize / 8];
+			kdf.GenerateBytes(keyBytes, 0, keyBytes.Length);
+
+			return new BigInteger(1, keyBytes);
+		}
+	}
+}