AES 암호화 예제(128Bit)

public class CipherUtil {
    private Log LOG = LogFactory.getLog(this.getClass());
    
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        CipherUtil cu = new CipherUtil();
        Calendar cal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssss");
        String key = sdf.format(cal.getTime());
        System.out.println("key: " + key);
        String text = "가나다라마바사＠★아&자@12!@#$%";
        String encryptText = null;
        String decryptText = null;

        try {
           encryptText = cu.encryptAES(text, key);
           decryptText = cu.decryptAES(encryptText, key);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("encryptText: " + encryptText);
        System.out.println("beforeText : " + text);
        System.out.println("decryptText: " + decryptText);
        // 2011051813190051
        // abcdefgh01234567
    }

    // key는 16바이트로 구성 되어야 한다.
    private String encryptAES(String s, String key) throws Exception {
        String encrypted = null;
        try {
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes(), "AES");
            
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
            
            encrypted = byteArrayToHex(cipher.doFinal(s.getBytes()));
            return encrypted;
        } catch (Exception e) {
            if (LOG.isErrorEnabled()) {
                LOG.error(e.getMessage(), e);
            }
            throw e;
        }
    }
    
    // key는 16 바이트로 구성 되어야 한다.
    private String decryptAES(String s, String key) throws Exception {
        String decrypted = null;
        try {
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes(), "AES");
            
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.DECRYPT_MODE, skeySpec);
            decrypted = new String(cipher.doFinal(hexToByteArray(s)));
            return decrypted;
        } catch (Exception e) {
            if (LOG.isErrorEnabled()) {
                LOG.error(e.getMessage(), e);
            }
            throw e;
        }
    }
    
    private byte[] hexToByteArray(String s) {
        byte[] retValue = null;
        if (s != null && s.length() != 0) {
            retValue = new byte[s.length() / 2];
            for (int i = 0; i < retValue.length; i++) {
                retValue[i] = (byte) Integer.parseInt(s.substring(2 * i, 2 * i + 2), 16);
            }
        }
        return retValue;
    }
    
    private String byteArrayToHex(byte buf[]) {
        StringBuffer strbuf = new StringBuffer(buf.length * 2);
        for (int i = 0; i < buf.length; i++) {
            if (((int) buf[i] & 0xff) < 0x10) {
                strbuf.append("0");
            }
            strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
        }
        
        return strbuf.toString();
    }
}

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