Question

I have a RSA public key in String format and I want to encrypt a string using the same to Base 64. Here is the code that I am using for this:

function encrypt(String pin){ 
  String key = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAiOnM5t6w2ZD6dpA4/MzSTAOt0IYpnsmGSAIfIVgGntI+fI4wbvUvMIhaLN3fHrjyuNGFdYw+yuoXYkapajt6VTZJniaatSiq6bwQ7R0UAop6haFSAwjnmReqexJvcKyqUsTfcfFypPpsYRewh/48/jmc/6ND+ugxDd52prkPUrbj+nnO0z3DBoUCpgDMRvW2hWXv6kZ654gp+wIAQnxbdwRMy6FZbrHjkA3tc6U0CHK+KjxAfzWAK+yI+ofskM4qk50J7y9hUZ7lLikqWZWKiqh8xiDk1kgu+FIjVh+fylKpa3gWmPPn0fSpBJjuenc1OQVmZ718a3388DjzFlYOLwIDAQAB";
  byte[] sigBytes2 = Base64.decode(key, Base64.DEFAULT);
  Log.d("WS", "new key is: " + key);
  try {
    PublicKey publicKey = KeyFactory.getInstance("RSA")
        .generatePublic(new X509EncodedKeySpec(sigBytes2));
    encryptedBase64PIN = encode(publicKey, pin);
    Log.d("WSA", "encoded key is: " + encryptedBase64PIN);
    // getSecToken();
  } catch (Exception e) {
    e.printStackTrace();
  }
}

public static String encode(Key publicKey, String data)
    throws NoSuchAlgorithmException, NoSuchPaddingException,
    InvalidKeyException, IllegalBlockSizeException, BadPaddingException {

  byte[] byteData = data.getBytes(); // convert string to byte array

  Cipher cipher = Cipher.getInstance("RSA/ECB/NoPadding");       
  cipher.init(Cipher.ENCRYPT_MODE, publicKey);      
  byte[] encryptedByteData = cipher.doFinal(byteData);

  String s = Base64.encodeToString(encryptedByteData, Base64.NO_WRAP);
  return s; // convert encrypted byte array to string and return it
}

When I send the same output to the server, it says “cannot decrypt the PIN”. Why is this?

Answer 1

When I send the same output to the server, it says “cannot decrypt the PIN”. Why is this?

There could be many reasons for this. If you have the code for the server decryption, please add it to your question.

Reasons may include:

• Wrong encryption mode. You’ve selected RSA/ECB/NoPadding but perhaps the server is expecting something else?

• Base64 encoding – is the server definitely expecting this?

• The message is “cannot decrypt PIN”. If the data you are encrypting is the PIN are you sure you should be encrypting ASCII bytes?