ZendoXorEncryption

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

public class ZendosXorEncryption {
  public byte[] xor(byte[] keyBytes, int keyOffset, byte[] inputBytes) {
    if ((keyOffset < 0) || (keyBytes.length < keyOffset + inputBytes.length))
      throw new Exception("Offset is illegal: " + keyOffset);
    if (inputBytes.length > keyBytes.length)
      throw new Exception("key is not big enough");
    byte[] outputBytes = new byte[inputBytes.length];
    for (int i = 0; i < outputBytes.length; i++)
      outputBytes[i] = ((byte)(keyBytes[(keyOffset + i)] ^ inputBytes[i]));
    return outputBytes;
  }

  public byte[] xor(byte[] keyBytes, int keyOffset, byte[] inputBytes, int headerInt) {
    int i = 0;
    if ((keyOffset < 0) || (keyBytes.length < keyOffset + inputBytes.length))
      throw new Exception("Offset is illegal: " + keyOffset);
    if (inputBytes.length > keyBytes.length)
      throw new Exception("key is not big enough");
    byte[] outputBytes = new byte[8 + inputBytes.length];
    byte[] headerAsbytes = intToLittleEndianBytes(headerInt);
    System.arraycopy(headerAsbytes, 0, outputBytes, 0, headerAsbytes.length);
    byte[] keyOffsetAsBytes = intToLittleEndianBytes(keyOffset);
    System.arraycopy(keyOffsetAsBytes, 0, outputBytes, headerAsbytes.length, keyOffsetAsBytes.length);
    for (int j = headerAsbytes.length + keyOffsetAsBytes.length; j < outputBytes.length; j++) {
      outputBytes[j] = ((byte)(keyBytes[(keyOffset + i)] ^ inputBytes[i]));
      i++;
    }
    return outputBytes;
  }

  public static byte[] intToLittleEndianBytes(int intToEncode) {
    ByteBuffer localByteBuffer = ByteBuffer.allocate(4);
    localByteBuffer.putInt(intToEncode);
    localByteBuffer.order(ByteOrder.LITTLE_ENDIAN);
    return localByteBuffer.array();
  }
}