Appendix

Appendix

Sample AES Code

public class AESCrypto {
    private String secretKey;
    public AESCrypto() {}
    public AESCrypto(String secretKey) {
        this.secretKey = secretKey;
    }
    public String encrypt(String data)
    throws UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        String endata = "";
        byte byteKey[] = (byte[]) hex2byte(secretKey);
        SecretKeySpec skeySpec = new SecretKeySpec(byteKey, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(1, skeySpec);
        byte bytedata[] = cipher.doFinal(data.getBytes());
        endata = asHex(bytedata);
        return endata;
    }
    public String decrypt(String encrypted)
    throws UnsupportedEncodingException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        byte byteKey[] = (byte[]) hex2byte(secretKey);
        byte byteEncData[] = hex2byte(encrypted);
        SecretKeySpec skeySpec = new SecretKeySpec(byteKey, "AES");
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        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(2, skeySpec);
        byte original[] = cipher.doFinal(byteEncData);
        String originalString = new String(original);
        return originalString;
    }
    public String asHex(byte buf[]) {
        StringBuffer strbuf = new StringBuffer(buf.length * 2);
        for (int i = 0; i < buf.length; i++) {
            if ((buf[i] & 0xff) < 16) {
                strbuf.append("0");
            }
            strbuf.append(Long.toString(buf[i] & 0xff, 16));
        }
        return strbuf.toString();
    }
    public static byte[] hex2byte(String s) {
        return hex2byte(s.getBytes(), 0, s.length() >> 1);
    }
    public static byte[] hex2byte(byte b[], int offset, int len) {
        byte d[] = new byte[len];
        for (int i = 0; i < len * 2; i++) {
            int shift = i % 2 == 1 ? 0 : 4;
            d[i >> 1] |= Character.digit((char) b[offset + i], 16) << shift;
        }
        return d;
    }
}