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The FIPS 140-3 Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms certified to FIPS 140-3 level 1. This jar contains JCE provider and low-level API for the BC-FJA version 2.0.0, FIPS Certificate #4743. Please see certificate for certified platform details.

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/***************************************************************/
/******    DO NOT EDIT THIS CLASS bc-java SOURCE FILE     ******/
/***************************************************************/
package org.bouncycastle.crypto.general;

import java.math.BigInteger;
import java.security.SecureRandom;

import org.bouncycastle.crypto.internal.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.internal.AsymmetricCipherKeyPairGenerator;
import org.bouncycastle.crypto.internal.KeyGenerationParameters;
import org.bouncycastle.crypto.internal.params.EcDomainParameters;
import org.bouncycastle.crypto.internal.params.EcPrivateKeyParameters;
import org.bouncycastle.crypto.internal.params.EcPublicKeyParameters;
import org.bouncycastle.math.ec.ECConstants;
import org.bouncycastle.math.ec.ECMultiplier;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.math.ec.FixedPointCombMultiplier;
import org.bouncycastle.math.ec.WNafUtil;

class EcKeyPairGenerator
    implements AsymmetricCipherKeyPairGenerator, ECConstants
{
    EcDomainParameters params;
    SecureRandom        random;

    public void init(
        KeyGenerationParameters param)
    {
        EcKeyGenerationParameters ecP = (EcKeyGenerationParameters)param;

        this.random = ecP.getRandom();
        this.params = ecP.getDomainParameters();

        if (this.random == null)
        {
            throw new IllegalArgumentException("No random provided where one required.");
        }
    }

    /**
     * Given the domain parameters this routine generates an EC key
     * pair in accordance with X9.62 section 5.2.1 pages 26, 27.
     */
    public AsymmetricCipherKeyPair generateKeyPair()
    {
        BigInteger n = params.getN();
        int nBitLength = n.bitLength();
        int minWeight = nBitLength >>> 2;

        BigInteger d;
        for (;;)
        {
            d = new BigInteger(nBitLength, random);

            if (d.compareTo(TWO) < 0  || (d.compareTo(n) >= 0))
            {
                continue;
            }

            /*
             * Require a minimum weight of the NAF representation, since low-weight primes may be
             * weak against a version of the number-field-sieve for the discrete-logarithm-problem.
             *
             * See "The number field sieve for integers of low weight", Oliver Schirokauer.
             */
            if (WNafUtil.getNafWeight(d) < minWeight)
            {
                continue;
            }

            break;
        }

        ECPoint Q = createBasePointMultiplier().multiply(params.getG(), d);

        return new AsymmetricCipherKeyPair(
            new EcPublicKeyParameters(Q, params),
            new EcPrivateKeyParameters(d, params));
    }

    protected ECMultiplier createBasePointMultiplier()
    {
        return new FixedPointCombMultiplier();
    }
}