ByteBuffer Decryption

Question

I have been writing a VoIP program and have used the code below to encrypt some data for sending in Java:

private byte[] encryptData(byte[] data){
 ByteBuffer unwrapEncrypt = ByteBuffer.allocate(data.length + 2);
 short authKey = 10;
 unwrapEncrypt.putShort(authKey);
 ByteBuffer plainText = ByteBuffer.wrap(data);
 for (int i = 0; i < keys.size(); i++) {
 for (int j = 0; j < data.length / 4; j++) {
 int fourByte = plainText.getInt();
 fourByte = fourByte ^ keys.get(i); // XOR operation with key
 if(i == keys.size() - 1) {
 unwrapEncrypt.putInt(fourByte);
 }
 }
 plainText.rewind();
 }
 return unwrapEncrypt.array();
}

and have tried doing the opposite to decrypt it on the other end:

 ByteBuffer cipherText = ByteBuffer.wrap(block);
 short authKey = cipherText.getShort();
 if (authKey == 10) {
 for (int i = 0; i < keys.size(); i++) {
 for (int j = 0; j < block.length / 4; j++) {
 int fourByte = cipherText.getInt();
 fourByte = fourByte ^ keys.get(i); // XOR decrypt
 if (i == keys.size() - 1) {
 unwrapDecrypt.putInt(fourByte);
 }
 }
 cipherText.rewind();
 }
 byte[] decryptedBlock = unwrapDecrypt.array();

However, the data I receive is still somewhat encrypted and as such the audio is garbled. The keys used are in reverse order in the receiver, so that should not be an issue. I assume the issue is with the indexing of ByteBuffers but am unsure how to proceed.

• Iłya Bursov: what happens if original data is 3 bytes length?
• Iłya Bursov: why do you need to iterate over all keys, if only last key is actually used to populate unwrapEncrypt?
• user85421: Problem: "The keys used are in reverse order" but only the last key is relevant, assuming first and last key are different (see Iłya's second comment - the first comment also points a possible problem)
• user85421: you probably wanted to exchange the inner and the outer loops, that is, the key loop is the inner one. (by the way, the order of XOR values is not relevant, only which values are used is relevant - as coded, only the last key is used; previous calculated values are ignored)
• rzwitserloot: As a separate note, you should not call this 'encryption'. [A] XORing it multiple times adds no security in any way - the operation d XOR k1 XOR k2 XOR k3 XOR k4 is mathematically equivalent to d XOR kp where kp is simply x1 XOR k2 XOR k3 XOR k4 on its own; hence, this adds nothing, and your code is 'silly' (calculate kp once and just XOR with that, eliminates a loop!), [B] "decrypting" this is child's play. Call it perhaps 'obfuscation' - make sure your words don't mislead.