I have a project where a user needs to store a U32 encrypted on a blockchain such that they can recover it themselves: the user will always have their key available but may "forget" the U32 value. No other party needs to decode the information, but the plaintext will eventually also be public on the chain.
The user has an entropy seed from which an infinite number of keys of any size can be deterministically derived. I was looking to using a single block of AES but it occurred to me that a simple XOR would also suffice. Assuming the user derives a unique "key" every time they perform this type of operation, is there any reason to do anything more complicated than that?