Decryption result not consistent

Question

I have two instances of my service that does the encryption and decryption running in cloud. The decryption fails sometimes with 'decryption failed' error. I guess this is because each instance has its own Aead instance. How can i solve this issue?

    public class Utils {
        private static final Logger log = LoggerFactory.getLogger(Utils.class);
        private Aead aead;
        private static Utils utils;

        private Utils() {
            try {
                AeadConfig.register();
                KeysetHandle keysetHandle = KeysetHandle.generateNew(AeadKeyTemplates.AES128_GCM);
                aead = AeadFactory.getPrimitive(keysetHandle);
            } catch (GeneralSecurityException e) {
                log.error(String.format("Error occured: %s",e.getMessage())).log();
            }
        }

        public static Utils getInstance() {
            if(null == utils) {
                utils = new Utils();
            }
        return utils;
    }

    public String encrypt(String text) throws GeneralSecurityException, UnsupportedEncodingException {
        byte[] plainText = text.getBytes("ISO-8859-1");
        byte[] additionalData = null;
        byte[] cipherText = aead.encrypt(plainText,additionalData);

        String output = Base64.getEncoder().encodeToString(cipherText);
        return output;
    }

    public String decrypt(String text) throws GeneralSecurityException, UnsupportedEncodingException {
        byte[] cipherText = Base64.getDecoder().decode(text);
        byte[] additionalData = null;
        byte[] decipheredData = aead.decrypt(cipherText,additionalData);

        String output = new String(decipheredData,"ISO-8859-1");
        return output;
    }

 @Test
    public void encrypt() throws IOException, GeneralSecurityException {
        String encryptedText = cryptographicUtils.encrypt("Hello World");
        assertThat(encryptedText, Matchers.notNullValue());
    }

    @Test
    public void decrypt() throws IOException, GeneralSecurityException {
        String encryptedText = cryptographicUtils.encrypt("Hello 123456");
        String decrypedText = cryptographicUtils.decrypt(encryptedText);

        assertThat(decrypedText, Matchers.is("Hello 123456"));
    }

I am getting consistent result if only one instance is running...

Answer 1

I will have to use the same keyset to encrypt and decrypt. I am able to resolve the issue by storing the keyset in a physical location and use it to create Aead instance. With this change all instances of my service able to decrypt string successfully