- Alice and Bob use (cryptographically secure, hardware-rng generated) 4096 bit keys.
- Each message is encrypted using a new key; meaning: once a key is used, it's destroyed.
- Alice and Bob only need to encrypt/decrypt messages up to a length of 256 bytes.
- To keep it simple, key-exchange is not part of the picture and can be assumed 100% secure.
Since the 4096 bit keys practically represent 512 bytes, the key obviously holds enough random material so that it "could" be considered suitable for One-Time-Pad use (like in classical OTP cipher examples).
Looking at the above assumptions, would the use of a simple OTP-XOR cipher indeed be secure enough from a cryptographic point of view, or is it more advisable to use another crypto-algorithm (for example a block-cipher) for some specific reason? And if, why would it be more advisable to use another cipher?