if you only use the key one time, yes it would be a one time pad. But using it over and over is also an option, and nearly as secure. As long as the key never falls into the hands of someone else, yeah...it will be secure, simply because there is no "cheater" way to undo an XOR unless the pattern repeats. Also one other note to remember, if you transmit more than one message using this meathod, it gets slightly less secure with each message. "Technically" you can break it using two ciphertexts and a LOT of spare time, simply because you can XOR the word over and over on the key at different offsets and get "pieces" of the plaintext, which can then be used to obtain parts of the key, and try them against the other ciphertext. But anyway...enough about that....