Initial Commit

iTechSharp/srcbc/crypto/generators/GOST3410KeyPairGenerator.cs

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+using System;
+
+using Org.BouncyCastle.Asn1.CryptoPro;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Security;
+
+namespace Org.BouncyCastle.Crypto.Generators
+{
+	/**
+	 * a GOST3410 key pair generator.
+	 * This generates GOST3410 keys in line with the method described
+	 * in GOST R 34.10-94.
+	 */
+	public class Gost3410KeyPairGenerator
+		: IAsymmetricCipherKeyPairGenerator
+	{
+		private Gost3410KeyGenerationParameters param;
+
+		public void Init(
+			KeyGenerationParameters parameters)
+		{
+			if (parameters is Gost3410KeyGenerationParameters)
+			{
+				this.param = (Gost3410KeyGenerationParameters) parameters;
+			}
+			else
+			{
+				Gost3410KeyGenerationParameters kgp = new Gost3410KeyGenerationParameters(
+					parameters.Random,
+					CryptoProObjectIdentifiers.GostR3410x94CryptoProA);
+
+				if (parameters.Strength != kgp.Parameters.P.BitLength - 1)
+				{
+					// TODO Should we complain?
+				}
+
+				this.param = kgp;
+			}
+		}
+
+		public AsymmetricCipherKeyPair GenerateKeyPair()
+		{
+			SecureRandom random = param.Random;
+			Gost3410Parameters gost3410Params = param.Parameters;
+
+			BigInteger q = gost3410Params.Q;
+			BigInteger x;
+			do
+			{
+				x = new BigInteger(256, random);
+			}
+			while (x.SignValue < 1 || x.CompareTo(q) >= 0);
+
+			BigInteger p = gost3410Params.P;
+			BigInteger a = gost3410Params.A;
+
+			// calculate the public key.
+			BigInteger y = a.ModPow(x, p);
+
+			if (param.PublicKeyParamSet != null)
+			{
+				return new AsymmetricCipherKeyPair(
+					new Gost3410PublicKeyParameters(y, param.PublicKeyParamSet),
+					new Gost3410PrivateKeyParameters(x, param.PublicKeyParamSet));
+			}
+
+			return new AsymmetricCipherKeyPair(
+				new Gost3410PublicKeyParameters(y, gost3410Params),
+				new Gost3410PrivateKeyParameters(x, gost3410Params));
+		}
+	}
+}