Examples with RSAPrivateCrtKeyParameters org.gudy.bouncycastle.crypto.params.RSAPrivateCrtKeyParameters used on opensource projects

Example 1 with RSAPrivateCrtKeyParameters

use of org.gudy.bouncycastle.crypto.params.RSAPrivateCrtKeyParameters in project BiglyBT by BiglySoftware.

the class RSAEngine method processBlock.

/**
 * Process a single block using the basic RSA algorithm.
 *
 * @param in the input array.
 * @param inOff the offset into the input buffer where the data starts.
 * @param inLen the length of the data to be processed.
 * @return the result of the RSA process.
 * @exception DataLengthException the input block is too large.
 */
@Override
public byte[] processBlock(byte[] in, int inOff, int inLen) {
    if (inLen > (getInputBlockSize() + 1)) {
        throw new DataLengthException("input too large for RSA cipher.\n");
    } else if (inLen == (getInputBlockSize() + 1) && (in[inOff] & 0x80) != 0) {
        throw new DataLengthException("input too large for RSA cipher.\n");
    }
    byte[] block;
    if (inOff != 0 || inLen != in.length) {
        block = new byte[inLen];
        System.arraycopy(in, inOff, block, 0, inLen);
    } else {
        block = in;
    }
    BigInteger input = new BigInteger(1, block);
    byte[] output;
    if (key instanceof RSAPrivateCrtKeyParameters) {
        // 
        // we have the extra factors, use the Chinese Remainder Theorem - the author
        // wishes to express his thanks to Dirk Bonekaemper at rtsffm.com for
        // advice regarding the expression of this.
        // 
        RSAPrivateCrtKeyParameters crtKey = (RSAPrivateCrtKeyParameters) key;
        BigInteger p = crtKey.getP();
        BigInteger q = crtKey.getQ();
        BigInteger dP = crtKey.getDP();
        BigInteger dQ = crtKey.getDQ();
        BigInteger qInv = crtKey.getQInv();
        BigInteger mP, mQ, h, m;
        // mP = ((input mod p) ^ dP)) mod p
        mP = (input.remainder(p)).modPow(dP, p);
        // mQ = ((input mod q) ^ dQ)) mod q
        mQ = (input.remainder(q)).modPow(dQ, q);
        // h = qInv * (mP - mQ) mod p
        h = mP.subtract(mQ);
        h = h.multiply(qInv);
        // mod (in Java) returns the positive residual
        h = h.mod(p);
        // m = h * q + mQ
        m = h.multiply(q);
        m = m.add(mQ);
        output = m.toByteArray();
    } else {
        output = input.modPow(key.getExponent(), key.getModulus()).toByteArray();
    }
    if (forEncryption) {
        if (// have ended up with an extra zero byte, copy down.
        output[0] == 0 && output.length > getOutputBlockSize()) {
            byte[] tmp = new byte[output.length - 1];
            System.arraycopy(output, 1, tmp, 0, tmp.length);
            return tmp;
        }
        if (// have ended up with less bytes than normal, lengthen
        output.length < getOutputBlockSize()) {
            byte[] tmp = new byte[getOutputBlockSize()];
            System.arraycopy(output, 0, tmp, tmp.length - output.length, output.length);
            return tmp;
        }
    } else {
        if (// have ended up with an extra zero byte, copy down.
        output[0] == 0) {
            byte[] tmp = new byte[output.length - 1];
            System.arraycopy(output, 1, tmp, 0, tmp.length);
            return tmp;
        }
    }
    return output;
}

Example 2 with RSAPrivateCrtKeyParameters

use of org.gudy.bouncycastle.crypto.params.RSAPrivateCrtKeyParameters in project BiglyBT by BiglySoftware.

the class RSAKeyPairGenerator method generateKeyPair.

@Override
public AsymmetricCipherKeyPair generateKeyPair() {
    BigInteger p, q, n, d, e, pSub1, qSub1, phi;
    // 
    // p and q values should have a length of half the strength in bits
    // 
    int pbitlength = (param.getStrength() + 1) / 2;
    int qbitlength = (param.getStrength() - pbitlength);
    e = param.getPublicExponent();
    // 
    for (; ; ) {
        p = new BigInteger(pbitlength, 1, param.getRandom());
        if (p.mod(e).equals(ONE)) {
            continue;
        }
        if (!p.isProbablePrime(param.getCertainty())) {
            continue;
        }
        if (e.gcd(p.subtract(ONE)).equals(ONE)) {
            break;
        }
    }
    // 
    for (; ; ) {
        // 
        for (; ; ) {
            q = new BigInteger(qbitlength, 1, param.getRandom());
            if (q.equals(p)) {
                continue;
            }
            if (q.mod(e).equals(ONE)) {
                continue;
            }
            if (!q.isProbablePrime(param.getCertainty())) {
                continue;
            }
            if (e.gcd(q.subtract(ONE)).equals(ONE)) {
                break;
            }
        }
        // 
        // calculate the modulus
        // 
        n = p.multiply(q);
        if (n.bitLength() == param.getStrength()) {
            break;
        }
        // 
        // if we get here our primes aren't big enough, make the largest
        // of the two p and try again
        // 
        p = p.max(q);
    }
    if (p.compareTo(q) < 0) {
        phi = p;
        p = q;
        q = phi;
    }
    pSub1 = p.subtract(ONE);
    qSub1 = q.subtract(ONE);
    phi = pSub1.multiply(qSub1);
    // 
    // calculate the private exponent
    // 
    d = e.modInverse(phi);
    // 
    // calculate the CRT factors
    // 
    BigInteger dP, dQ, qInv;
    dP = d.remainder(pSub1);
    dQ = d.remainder(qSub1);
    qInv = q.modInverse(p);
    return new AsymmetricCipherKeyPair(new RSAKeyParameters(false, n, e), new RSAPrivateCrtKeyParameters(n, e, d, p, q, dP, dQ, qInv));
}