“Please, Don’t Roll Your Own Metaethics” by Wei Dai

One day, when I was an interning at the cryptography research department of a large software company, my boss handed me an assignment to break a pseudorandom number generator passed to us for review. Someone in another department invented it and planned to use it in their product, and wanted us to take a look first. This person must have had a lot of political clout or was especially confident in himself, because he refused the standard advice that anything an amateur comes up with is very likely to be insecure and he should instead use one of the established, off the shelf cryptographic algorithms, that have survived extensive cryptanalysis (code breaking) attempts. My boss thought he had to demonstrate the insecurity of the PRNG by coming up with a practical attack (i.e., a way to predict its future output based only on its past output, without knowing the secret key/seed). There were three permanent full time professional cryptographers working in the research department, but none of them specialized in cryptanalysis of symmetric cryptography (which covers such PRNGs) so it might have taken them some time to figure out an attack. My time was obviously less valuable and my [...] The original text contained 1 footnote which was omitted from this narration. --- First published: November 12th, 2025 Source: https://www.lesswrong.com/posts/KCSmZsQzwvBxYNNaT/please-don-t-roll-your-own-metaethics --- Narrated by TYPE III AUDIO.