com.connorbrezinsky.msg.security.Hash.java Source code

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Here is the source code for com.connorbrezinsky.msg.security.Hash.java

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/*   msg. Encrypted Messaging. For everyone.
Copyright (C) 2016 Connor Brezinsky
    
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
    
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
    
You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>
    
I ALSO STOLE THIS FROM STACK OVERFLOW OR SOMETHING NOT TOO SURE. 
SO IF ITS YOURS AND YOU HAVE AN ISSUE HIT ME UP
    
    
*/

package com.connorbrezinsky.msg.security;

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 Hash {

    // 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 = 50 * 1000;
    private static final int saltLen = 32;
    private static final int desiredKeyLen = 256;

    /**
     * Computes a salted PBKDF2 hash of given plaintext password suitable for
     * storing in a database. Empty passwords are not supported.
     */
    public static 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 static 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'");
        }
        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 static 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());
    }

}