AES加密，解密封装。以及解密异常解决

1.类的封装

public class Encryption {


    private final static String HEX = "0123456789ABCDEF";
    private static String seed = "zhou"; //加密，解密时需要的密码




    /**
     * aes加密时调用
     * 密码
     * @param cleartext 加密内容
     * @return
     * @throws Exception
     */
    public static String encrypt(String cleartext)
            throws Exception {
        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] result = encrypt(rawKey, cleartext.getBytes());
        return toHex(result);
    }


    /**
     * aes解密时调用
     *
     * @param
     * @param encrypted
     * @return
     * @throws Exception
     */
    public static String decrypt( String encrypted)
            throws Exception {
        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] enc = toByte(encrypted);
        byte[] result = decrypt(rawKey, enc);
        return new String(result);
    }


    private static byte[] getRawKey(byte[] seed) throws Exception {
        //创建AESkey的生产者
        KeyGenerator kgen = KeyGenerator.getInstance("AES");

//加入第二个参数后解决了，解密时pad block corrupted的异常
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG","Crypto");
        sr.setSeed(seed);
        kgen.init(128, sr); // 192 and 256 bits may not be available
        SecretKey skey = kgen.generateKey();
        byte[] raw = skey.getEncoded();
        return raw;
    }


    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        byte[] encrypted = cipher.doFinal(clear);
        return encrypted;
    }


    private static byte[] decrypt(byte[] raw, byte[] encrypted)
            throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        byte[] decrypted = cipher.doFinal(encrypted);
        return decrypted;
    }


    public static String toHex(String txt) {
        return toHex(txt.getBytes());
    }


    public static String fromHex(String hex) {
        return new String(toByte(hex));
    }


    public static byte[] toByte(String hexString) {
        int len = hexString.length() / 2;
        byte[] result = new byte[len];
        for (int i = 0; i < len; i++)
            result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
                    16).byteValue();
        return result;
    }


    public static String toHex(byte[] buf) {
        if (buf == null)
            return "";
        StringBuffer result = new StringBuffer(2 * buf.length);
        for (int i = 0; i < buf.length; i++) {
            appendHex(result, buf[i]);
        }
        return result.toString();
    }


    private static void appendHex(StringBuffer sb, byte b) {
        sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
    }
}

2.参考链接

http://blog.csdn.net/wujxiaoz/article/details/9036981

http://stackoverflow.com/questions/13389870/android-4-2-broke-my-aes-encrypt-decrypt-code