This is a one-time pad. Given a ciphertext D it's trivial to come up with a key K that "decrypts" D to whatever plaintext P you want (K = D XOR P). This is why

This is a one-time pad. Given a ciphertext D it's trivial to come up with a key K that "decrypts" D to whatever plaintext P you want (K = D XOR P). This is why one-time pads are immune to brute-force search.