package org.bouncycastle.crypto.generators;import org.bouncycastle.crypto.AsymmetricCipherKeyPairGenerator;import org.bouncycastle.crypto.KeyGenerationParameters;import org.bouncycastle.crypto.AsymmetricCipherKeyPair;import org.bouncycastle.crypto.params.GOST3410PrivateKeyParameters;import org.bouncycastle.crypto.params.GOST3410PublicKeyParameters;import org.bouncycastle.crypto.params.GOST3410KeyGenerationParameters;import org.bouncycastle.crypto.params.GOST3410Parameters;import java.math.BigInteger;import java.security.SecureRandom;/** * a GOST3410 key pair generator. * This generates GOST340 keys in line with the method described * in GOST R 34.10-94. */public class GOST3410KeyPairGenerator        implements AsymmetricCipherKeyPairGenerator    {        private static BigInteger ZERO = BigInteger.valueOf(0);        private GOST3410KeyGenerationParameters param;        public void init(            KeyGenerationParameters param)        {            this.param = (GOST3410KeyGenerationParameters)param;        }        public AsymmetricCipherKeyPair generateKeyPair()        {            BigInteger      p, q, a, x, y;            GOST3410Parameters   GOST3410Params = param.getParameters();            SecureRandom    random = param.getRandom();            q = GOST3410Params.getQ();            p = GOST3410Params.getP();            a = GOST3410Params.getA();            do            {                x = new BigInteger(256, random);            }            while (x.equals(ZERO) || x.compareTo(q) >= 0);            //            // calculate the public key.            //            y = a.modPow(x, p);            return new AsymmetricCipherKeyPair(                    new GOST3410PublicKeyParameters(y, GOST3410Params),                    new GOST3410PrivateKeyParameters(x, GOST3410Params));        }    }