| package org.bouncycastle.crypto.generators; |
| |
| import org.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); |
| } |
| } |