com.yukthi.utils.CryptoUtils.java Source code

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Here is the source code for com.yukthi.utils.CryptoUtils.java

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/*
 * The MIT License (MIT)
 * Copyright (c) 2015 "Yukthi Techsoft Pvt. Ltd." (http://yukthi-tech.co.in)
    
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.yukthi.utils;

import java.security.Key;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

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

import com.yukthi.utils.exceptions.InvalidArgumentException;

/**
 * Utility to encrypt/decrypt the string
 * 
 * @author akiran
 */
public class CryptoUtils {
    /**
     * Algorithm to use
     */
    private static final String ALGORITHM = "AES";

    /**
     * Transformation to use
     */
    private static final String TRANSFORMATION = "AES";

    /**
     * Encrypts the provided input and convert encrypted bytes into hex string
     * @param secretKey Secret key to use for encryption
     * @param input Input to be encrypted
     * @return encrypted and hex converted string
     */
    public static String encrypt(String secretKey, String input) {
        if (secretKey.length() != 16) {
            throw new InvalidArgumentException("Secret key should be of length 16. Specified secrey key length - ",
                    secretKey.length());
        }

        //convert input into bytes
        byte inputBytes[] = input.getBytes();

        //encrypt bytes
        byte encryptedBytes[] = doCrypto(Cipher.ENCRYPT_MODE, secretKey, inputBytes);

        //convert encrypted bytes into hex string
        return Hex.encodeHexString(encryptedBytes);
    }

    /**
     * Decrypts specified input. Input should be encrypted and hex string (the way it is generated
     * by {@link #encrypt(String, String)} method
     * @param secretKey Secret key to use for decryption
     * @param input Input hex string to be decrypted
     * @return Decrypted value
     */
    public static String decrypt(String secretKey, String input) {
        if (secretKey.length() != 16) {
            throw new InvalidArgumentException("Secret key should be of length 16. Specified secrey key length - ",
                    secretKey.length());
        }

        try {
            //decode input string hex string
            byte decodedBytes[] = Hex.decodeHex(input.toCharArray());

            //decrypt decoded bytes
            byte decryptedBytes[] = doCrypto(Cipher.DECRYPT_MODE, secretKey, decodedBytes);

            //convert and return decrypted bytes into string
            return new String(decryptedBytes);
        } catch (Exception ex) {
            throw new InvalidArgumentException(ex, "An error occurred while decrypting string - {}", input);
        }
    }

    /**
     * Encrypts/Decrypts input string using AES algorithm
     * @param cipherMode
     * @param secretKeyStr
     * @param input
     * @return
     */
    private static byte[] doCrypto(int cipherMode, String secretKeyStr, byte input[]) {
        try {
            Key secretKey = new SecretKeySpec(secretKeyStr.getBytes(), ALGORITHM);
            Cipher cipher = Cipher.getInstance(TRANSFORMATION);
            cipher.init(cipherMode, secretKey);

            return cipher.doFinal(input);
        } catch (Exception ex) {
            throw new InvalidArgumentException(ex, "Error encrypting/decrypting input bytes");
        }
    }
}