Add BouncyCastle PCL files v1.7.0

1 files changed, 40 insertions, 0 deletions

diff --git a/Crypto/src/crypto/generators/ElGamalKeyPairGenerator.cs b/Crypto/src/crypto/generators/ElGamalKeyPairGenerator.cs
new file mode 100644
index 000000000..227e7fe94
--- /dev/null
+++ b/Crypto/src/crypto/generators/ElGamalKeyPairGenerator.cs
@@ -0,0 +1,40 @@
+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 egp = param.Parameters;
+			DHParameters dhp = new DHParameters(egp.P, egp.G, null, 0, egp.L);
+
+			BigInteger x = helper.CalculatePrivate(dhp, param.Random);
+			BigInteger y = helper.CalculatePublic(dhp, x);
+
+			return new AsymmetricCipherKeyPair(
+                new ElGamalPublicKeyParameters(y, egp),
+                new ElGamalPrivateKeyParameters(x, egp));
+        }
+    }
+
+}