(Post-Quantum) Cryptographic Right Answers

Publishing “Cryptographic Right Answers” for developers is a tradition by now. Colin Percival started in 2009, Thomas Ptacek followed up in 2015, and then Latacora carried on in 2018 and 2024. It might feel too soon for an update, but so much has changed. The timeline of the post-quantum transition dramatically shifted in early 2026, and there is now consensus that it needs to complete by 2029. 2029! We have three years! The good news is that, despite what you might have heard, symmetric cryptography is going to be fine, because Grover does not matter. The bad news is that all asymmetric answers changed compared to 2018 and most even compared to 2024. The answers below assume you are not constrained by any specific compliance regime, although they are mostly compatible with FIPS 140.1 If you need to follow something stricter like CNSA 2.0, you’ll know. Just substitute as appropriate. Finally, remember the other big change of 2026: LLMs are very good at finding bugs now. “Get a review…