com.mobileman.kuravis.core.util.security.SecurityUtils.java Source code

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Here is the source code for com.mobileman.kuravis.core.util.security.SecurityUtils.java

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/*******************************************************************************
 * Copyright 2015 MobileMan GmbH
 * www.mobileman.com
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/
package com.mobileman.kuravis.core.util.security;

import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import java.security.SecureRandom;
import java.util.UUID;

import org.apache.commons.codec.binary.Base64;

/**
 * 
 */
public class SecurityUtils {

    // The higher the number of iterations the more
    // expensive computing the hash is for us
    // and also for a brute force attack.
    private static final int iterations = 10 * 1024;
    private static final int saltLen = 32;
    private static final int desiredKeyLen = 256;

    /**
     * @param length
     * @return random string
     */
    public static String getRandomString(int length) {
        String result = "";

        UUID uuid = UUID.randomUUID();
        result = uuid.toString().substring(0, length);

        return result;
    }

    /**
     * Computes a salted PBKDF2 hash of given plaintext password suitable for
     * storing in a database. Empty passwords are not supported.
     * 
     * @param password
     * @return hashed password
     * @throws Exception
     */
    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.
     * 
     * @param password
     * @param stored
     * @return true if both passwpord matches
     * @throws Exception
     */
    public static boolean check(String password, String stored) throws Exception {
        String[] saltAndPass = stored.split("\\$");
        if (saltAndPass.length != 2)
            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 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());
    }

}