HgPBf5n7

1public String encrypt(String plainText, String authenticationTag) throws GeneralSecurityException, IOException {
2        Cipher cipher = Cipher.getInstance(ALGORITHM_MODE_PADDING);
3        final int blockSize = cipher.getBlockSize();
4        SecretKey secretKey = readKeyFile(...);
5        byte[] plainTextByte = plainText.trim().getBytes(Charset.forName("UTF-8"));
6        byte[] ivBytes = generateIV();
7        cipher.init(Cipher.ENCRYPT_MODE, secretKey, new GCMParameterSpec(GCM_TAG_LENGTH, ivBytes));
8        cipher.updateAAD(authenticationTag.getBytes(Charset.forName("UTF-8")));
9        byte[] encryptedMessage = cipher.doFinal(plainTextByte);
10        byte iv_and_encryptedMessage[] = concatIvAndCipher(ivBytes, encryptedMessage, blockSize);
11        Base64.Encoder encoder = Base64.getEncoder().withoutPadding();
12        String iv_and_encryptedText = encoder.encodeToString(iv_and_encryptedMessage);
13        return iv_and_encryptedText;
14    }
15
16    public String decrypt(String iv_and_encryptedTextBase64, String authenticationTag)
17            throws GeneralSecurityException, IOException {
18        Cipher cipher = Cipher.getInstance(ALGORITHM_MODE_PADDING);
19        final int blockSize = cipher.getBlockSize();
20        Base64.Decoder decoder = Base64.getDecoder();
21        byte[] iv_and_encryptedMessage = decoder.decode(iv_and_encryptedTextBase64.trim());
22        byte[] ivBytes = extractIvFrom(iv_and_encryptedMessage, blockSize);
23        byte[] encryptedTextBytes = extractEncryptedMessageFrom(iv_and_encryptedMessage, blockSize);
24        SecretKey secretKey = readKeyFile(...);
25        cipher.init(Cipher.DECRYPT_MODE, secretKey, new GCMParameterSpec(GCM_TAG_LENGTH, ivBytes));
26        cipher.updateAAD(authenticationTag.getBytes(Charset.forName("UTF-8")));
27        byte[] decryptedByte = cipher.doFinal(encryptedTextBytes);
28        String decryptedMessage = new String(decryptedByte, Charset.forName("UTF-8"));
29        return decryptedMessage;
30    }