rsakeypairgenerator.java

进行与数字证书相关开发必须的java源码

// Decompiled by Jad v1.5.7g. Copyright 2000 Pavel Kouznetsov.
// Jad home page: http://www.geocities.com/SiliconValley/Bridge/8617/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi 
// Source File Name:   RSAKeyPairGenerator.java

package jit.crypto.generators;

import jit.crypto.*;
import jit.crypto.params.*;
import jit.math.BigInteger;

public class RSAKeyPairGenerator
    implements AsymmetricCipherKeyPairGenerator
{

    private static BigInteger ONE = BigInteger.valueOf(1L);
    private RSAKeyGenerationParameters param;

    public RSAKeyPairGenerator()
    {
    }

    public void init(KeyGenerationParameters param)
    {
        this.param = (RSAKeyGenerationParameters)param;
    }

    public AsymmetricCipherKeyPair generateKeyPair()
    {
        int pbitlength = (param.getStrength() + 1) / 2;
        int qbitlength = param.getStrength() - pbitlength;
        BigInteger e = param.getPublicExponent();
        BigInteger p;
        do
            p = new BigInteger(pbitlength, param.getCertainty(), param.getRandom());
        while(!e.gcd(p.subtract(ONE)).equals(ONE));
        BigInteger q;
        BigInteger n;
        do
        {
            do
                q = new BigInteger(qbitlength, param.getCertainty(), param.getRandom());
            while(!e.gcd(q.subtract(ONE)).equals(ONE) || p.equals(q));
            n = p.multiply(q);
            if(n.bitLength() == param.getStrength())
                break;
            p = p.max(q);
        } while(true);
        BigInteger phi;
        if(p.compareTo(q) < 0)
        {
            phi = p;
            p = q;
            q = phi;
        }
        BigInteger pSub1 = p.subtract(ONE);
        BigInteger qSub1 = q.subtract(ONE);
        phi = pSub1.multiply(qSub1);
        BigInteger d = e.modInverse(phi);
        BigInteger dP = d.remainder(pSub1);
        BigInteger dQ = d.remainder(qSub1);
        BigInteger qInv = q.modInverse(p);
        return new AsymmetricCipherKeyPair(new RSAKeyParameters(false, n, e), new RSAPrivateCrtKeyParameters(n, e, d, p, q, dP, dQ, qInv));
    }

}