private static byte[] xor(final byte[] x, final byte[] y) {
    assert x.length == y.length;
    int len = x.length;
    byte[] res = new byte[len];
    for (int i = 0; i < len; i++) {
      res[i] = (byte) (x[i] ^ y[i]);
    }
    return res;
  }
Computes the xor of two byte arrays of equal size.
java_src/src/main/java/com/google/crypto/tink/subtle/AesEaxJce.java