package com.google.bitcoin.bouncycastle.crypto.generators; import com.google.bitcoin.bouncycastle.crypto.params.DHParameters; import java.math.BigInteger; import java.security.SecureRandom; public class DHParametersGenerator { private int size; private int certainty; private SecureRandom random; private static final BigInteger TWO = BigInteger.valueOf(2); /** * Initialise the parameters generator. * * @param size bit length for the prime p * @param certainty level of certainty for the prime number tests * @param random a source of randomness */ public void init( int size, int certainty, SecureRandom random) { this.size = size; this.certainty = certainty; this.random = random; } /** * which generates the p and g values from the given parameters, * returning the DHParameters object. * <p> * Note: can take a while... */ public DHParameters generateParameters() { // // find a safe prime p where p = 2*q + 1, where p and q are prime. // BigInteger[] safePrimes = DHParametersHelper.generateSafePrimes(size, certainty, random); BigInteger p = safePrimes[0]; BigInteger q = safePrimes[1]; BigInteger g = DHParametersHelper.selectGenerator(p, q, random); return new DHParameters(p, g, q, TWO, null); } }