com.paypal.utilities.AESDecrypt.java Source code

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Here is the source code for com.paypal.utilities.AESDecrypt.java

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/*
 * @(#){AESDecrypt.java}
 *
 * Copyright(coffee) 2013, Bill Me Later Inc and/or its affiliates. All rights reserved.
 * BILL ME LATER INC PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.paypal.utilities;

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

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.spec.KeySpec;

/**
 * Perform AES Decryption
 */
public class AESDecrypt {
    private static final byte[] SALT = { (byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32, (byte) 0x56,
            (byte) 0x35, (byte) 0xE3, (byte) 0x03 };
    private static final int ITERATION_COUNT = 65536;
    private static final int KEY_LENGTH = 128;
    private static final int IV_LENGTH = 16;
    private static final String passphrase = "PASSWORDPASSPHRASE";

    private Cipher eCipher;
    private Cipher dCipher;
    private byte[] encrypt;

    public AESDecrypt(String encryptedString) throws Exception {
        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
        KeySpec keySpec = new PBEKeySpec(passphrase.toCharArray(), SALT, ITERATION_COUNT, KEY_LENGTH);
        SecretKey secretKeyTemp = secretKeyFactory.generateSecret(keySpec);
        SecretKey secretKey = new SecretKeySpec(secretKeyTemp.getEncoded(), "AES");

        encrypt = Base64.decodeBase64(encryptedString.getBytes());

        eCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        eCipher.init(Cipher.ENCRYPT_MODE, secretKey);

        byte[] iv = extractIV();
        dCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        dCipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(iv));
    }

    private byte[] extractIV() {
        byte[] iv = new byte[IV_LENGTH];
        System.arraycopy(encrypt, 0, iv, 0, iv.length);
        return iv;
    }

    public String decrypt() throws Exception {
        byte[] bytes = extractCipherText();

        byte[] decrypted = decrypt(bytes);
        return new String(decrypted, "UTF8");
    }

    private byte[] extractCipherText() {
        byte[] ciphertext = new byte[encrypt.length - IV_LENGTH];
        System.arraycopy(encrypt, 16, ciphertext, 0, ciphertext.length);
        return ciphertext;
    }

    public byte[] decrypt(byte[] encrypt) throws Exception {
        return dCipher.doFinal(encrypt);
    }
}