Initial Commit

iTechSharp/srcbc/crypto/generators/ElGamalKeyPairGenerator.cs

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+using System;
+
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+
+namespace Org.BouncyCastle.Crypto.Generators
+{
+    /**
+     * a ElGamal key pair generator.
+     * <p>
+     * This Generates keys consistent for use with ElGamal as described in
+     * page 164 of "Handbook of Applied Cryptography".</p>
+     */
+    public class ElGamalKeyPairGenerator
+		: IAsymmetricCipherKeyPairGenerator
+    {
+        private ElGamalKeyGenerationParameters param;
+
+        public void Init(
+			KeyGenerationParameters parameters)
+        {
+            this.param = (ElGamalKeyGenerationParameters) parameters;
+        }
+
+        public AsymmetricCipherKeyPair GenerateKeyPair()
+        {
+			DHKeyGeneratorHelper helper = DHKeyGeneratorHelper.Instance;
+			ElGamalParameters elParams = param.Parameters;
+
+			BigInteger p = elParams.P;
+			BigInteger x = helper.CalculatePrivate(p, param.Random, elParams.L);
+			BigInteger y = helper.CalculatePublic(p, elParams.G, x);
+
+			return new AsymmetricCipherKeyPair(
+                new ElGamalPublicKeyParameters(y, elParams),
+                new ElGamalPrivateKeyParameters(x, elParams));
+        }
+    }
+
+}