Initial Commit

iTechSharp/srcbc/crypto/generators/DsaKeyPairGenerator.cs

@@ -0,0 +1,56 @@
+using System;
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.Parameters;
+
+namespace Org.BouncyCastle.Crypto.Generators
+{
+    /**
+     * a DSA key pair generator.
+     *
+     * This Generates DSA keys in line with the method described
+     * in FIPS 186-2.
+     */
+    public class DsaKeyPairGenerator
+		: IAsymmetricCipherKeyPairGenerator
+    {
+        private DsaKeyGenerationParameters param;
+
+		public void Init(
+			KeyGenerationParameters parameters)
+        {
+			if (parameters == null)
+				throw new ArgumentNullException("parameters");
+
+			// Note: If we start accepting instances of KeyGenerationParameters,
+			// must apply constraint checking on strength (see DsaParametersGenerator.Init)
+
+			this.param = (DsaKeyGenerationParameters) parameters;
+        }
+
+		public AsymmetricCipherKeyPair GenerateKeyPair()
+        {
+            DsaParameters dsaParams = param.Parameters;
+            SecureRandom random = param.Random;
+
+			BigInteger q = dsaParams.Q;
+			BigInteger x;
+
+			do
+            {
+                x = new BigInteger(160, random);
+            }
+            while (x.SignValue == 0 || x.CompareTo(q) >= 0);
+
+            //
+            // calculate the public key.
+            //
+			BigInteger y = dsaParams.G.ModPow(x, dsaParams.P);
+
+			return new AsymmetricCipherKeyPair(
+                new DsaPublicKeyParameters(y, dsaParams),
+                new DsaPrivateKeyParameters(x, dsaParams));
+        }
+	}
+}