[berbc]

As pointed out by some of you, this looks more like permutation of sequences. Also, since a symmetric cipher is used, I'm surprised the author didn't mention Black and Rogaway [1].

Their algorithm is a permutation (int -> int) that works on a domain of any size up to a limit. A typical application for this is encrypting credit card numbers so that the ciphertext still looks like a credit card number (non-trivial because the size of domain isn't a power of two) or efficiently shuffling sequences, randomly in appearance but repeatably if you know the seed.

For instance, this is used by Masscan to randomize the order in which IP addresses and ports are scanned [2]. I've built a Python package that could help you use this algorithm [3] (mostly for fun, but maybe that's useful, let me know :)).

[1]: https://en.wikipedia.org/wiki/Format-preserving_encryption#T... [2]: https://github.com/robertdavidgraham/masscan/blob/6c15edc280... [3]: https://github.com/bbc2/shuffled