http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.crypto.agreement.srp;

import java.math.BigInteger;

import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.params.SRP6GroupParameters;


Generates new SRP verifier for user

/**
 * Generates new SRP verifier for user
 */
public class SRP6VerifierGenerator
{
    protected BigInteger N;
    protected BigInteger g;
    protected Digest digest;

    public SRP6VerifierGenerator()
    {
    }

    
Initialises generator to create new verifiers

Params:
  • N – The safe prime to use (see DHParametersGenerator)
  • g – The group parameter to use (see DHParametersGenerator)
  • digest – The digest to use. The same digest type will need to be used later for the actual authentication
attempt. Also note that the final session key size is dependent on the chosen digest.
/**
     * Initialises generator to create new verifiers
     * @param N The safe prime to use (see DHParametersGenerator)
     * @param g The group parameter to use (see DHParametersGenerator)
     * @param digest The digest to use. The same digest type will need to be used later for the actual authentication
     * attempt. Also note that the final session key size is dependent on the chosen digest.
     */
    public void init(BigInteger N, BigInteger g, Digest digest)
    {
        this.N = N;
        this.g = g;
        this.digest = digest;
    }

    public void init(SRP6GroupParameters group, Digest digest)
    {
        this.N = group.getN();
        this.g = group.getG();
        this.digest = digest;
    }

    
Creates a new SRP verifier

Params:
  • salt – The salt to use, generally should be large and random
  • identity – The user's identifying information (eg. username)
  • password – The user's password
Returns:A new verifier for use in future SRP authentication
/**
     * Creates a new SRP verifier
     * @param salt The salt to use, generally should be large and random
     * @param identity The user's identifying information (eg. username)
     * @param password The user's password
     * @return A new verifier for use in future SRP authentication
     */
    public BigInteger generateVerifier(byte[] salt, byte[] identity, byte[] password)
    {
        BigInteger x = SRP6Util.calculateX(digest, N, salt, identity, password);

        return g.modPow(x, N);
    }
}