RSA KeyGenerator Set

1. 암호화 처리

	/**
     * 암호화 처리
     * @param publicKey
     * @param plainText
     * @return
     * @throws InvalidKeyException
     * @throws NoSuchPaddingException
     * @throws NoSuchAlgorithmException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     * @throws UnsupportedEncodingException
     */
    public static String encryptRSA(PublicKey publicKey, String plainText)
            throws InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {

        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);

        byte[] ecryptedBytes = cipher.doFinal(plainText.getBytes("utf-8"));
        String ecryptedString = Base64.getEncoder().encodeToString(ecryptedBytes);

        logger.info("##### ecryptedString {}", ecryptedString);

        return ecryptedString;
    }

.
2. 복호화 처리

	/**
     * 복호화 처리
     * @param privateKey
     * @param securedText
     * @return
     * @throws Exception
     */
    public static String decryptRSA(PrivateKey privateKey, String securedText) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        byte[] securedBytes = Base64.getDecoder().decode(securedText.getBytes());
        String securedString = new String(securedBytes, "utf-8");

        byte[] decryptedBytes = cipher.doFinal(securedBytes);
        String decryptedString = new String(decryptedBytes, "utf-8");

        logger.debug("##### decryptedString {}", decryptedString);

        return decryptedString;
    }

.
3. 테스트 케이스 작성

@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {RSAKeyGenerator.class})
public class RSAKeyGenerator {

    @Test
    public void testRSAKeyGenerator() throws Exception {

        KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
        generator.initialize(512); // key size 설정
        KeyPair keyPair = generator.generateKeyPair();

        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey  publicKey  = keyPair.getPublic();
        PrivateKey privateKey = keyPair.getPrivate();

        RSAPublicKeySpec publicKeySpec = (RSAPublicKeySpec) keyFactory.getKeySpec(publicKey, RSAPublicKeySpec.class);

        // publicKey / UI에서 사용가능 - 4번 참고
        String publicKeyModulus = publicKeySpec.getModulus().toString(16);
        String publicKeyExponent = publicKeySpec.getPublicExponent().toString(16);

        String e_username = SecurityUtils.encryptRSA(publicKey, "admin1");
        String e_password = SecurityUtils.encryptRSA(publicKey, "1");

        String de_username = SecurityUtils.decryptRSA(privateKey, e_username);
        String de_password = SecurityUtils.decryptRSA(privateKey, e_password);
    }
}

4. UI(화면) 암호화 전송 ( html / script )

    <!--순서에 주의-->
    <script src="/assets/js/rsa/rsa.js"></script>
    <script src="/assets/js/rsa/jsbn.js"></script>
    <script src="/assets/js/rsa/prng4.js"></script>
    <script src="/assets/js/rsa/rng.js"></script>
    
    ... 
    
    const rsaPublicKeyModulus = document.getElementById("publicKeyModulus").value;
    const rsaPublicKeyExponent = document.getElementById("publicKeyExponent").value;

    const rsa = new RSAKey();
    rsa.setPublic(rsaPublicKeyModulus, rsaPublicKeyExponent);

    // 사용자ID와 비밀번호를 RSA로 암호화한다.
    var securedUsername = rsa.encrypt(username);
    var securedPassword = rsa.encrypt(password);

끝~~