Util.PassGen.java Source code

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Here is the source code for Util.PassGen.java

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/*
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package Util;

/**
 *
 * @author Deamon
 */
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import java.security.SecureRandom;
import org.apache.commons.codec.binary.Base64;

public class PassGen {

    // The higher the number of iterations the more 
    // expensive computing the hash is for us and
    // also for an attacker.
    private static final int iterations = 20 * 1000;
    private static final int saltLen = 32;
    private static final int desiredKeyLen = 100;

    public PassGen() {
    }

    /**
     * Computes a salted PBKDF2 hash of given plaintext password suitable for
     * storing in a database. Empty passwords are not supported.
     */
    public String getSaltedHash(String password) throws Exception {
        byte[] salt = SecureRandom.getInstance("SHA1PRNG").generateSeed(saltLen);
        // store the salt with the password
        return Base64.encodeBase64String(salt) + "$" + hash(password, salt);
    }

    /**
     * Checks whether given plaintext password corresponds to a stored salted
     * hash of the password.
     */
    public boolean check(String password, String stored) throws Exception {

        String[] saltAndPass = stored.split("\\$");
        if (saltAndPass.length != 2) {
            /* throw new IllegalStateException(
             "The stored password have the form 'salt$hash'");
             */
            return false;
        }
        String hashOfInput = hash(password, Base64.decodeBase64(saltAndPass[0]));
        return hashOfInput.equals(saltAndPass[1]);
    }

    // using PBKDF2 from Sun, an alternative is https://github.com/wg/scrypt
    // cf. http://www.unlimitednovelty.com/2012/03/dont-use-bcrypt.html
    private String hash(String password, byte[] salt) throws Exception {
        if (password == null || password.length() == 0) {
            throw new IllegalArgumentException("Empty passwords are not supported.");
        }
        SecretKeyFactory f = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
        SecretKey key = f.generateSecret(new PBEKeySpec(password.toCharArray(), salt, iterations, desiredKeyLen));
        return Base64.encodeBase64String(key.getEncoded());
    }

}