암호화 SHA-256

    // 암호화 하기
    public static String sha256(String msg)  throws NoSuchAlgorithmException {

        String result ="";
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(msg.getBytes());
        byte[] byteData = md.digest();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < byteData.length; i++) {
            sb.append(Integer.toString((byteData[i] & 0xFF) + 256, 16).substring(1));
        }
        result = sb.toString();
        return result;
    }