Re: alleged-RC4

Another thing that is pretty obvious is that this kind of cypher is not suitable for certain applications. For example, if you wanted to encrypt individually a lot of different files on your disk, all using the same key, this kind of stream cypher would be totally unsuitable. Any success in guessing the plaintext which corresponds to a given cyphertext reveals the XOR stream that the key generates, and that is the same stream that would be XOR'd to encrypt any other file with the same key. Doing this would be similar to re-using a "one time" pad for many encryptions. This kind of cypher is more appropriate for a communications channel where the key is never re-used, and the two sides can keep persistent and synchronized state. Hal