hiq's comment was not about Whisperfish but about the presage library. My comment can be read as "Whisperfish wrote their own implementation of the signal protocol" - which is wrong. (Sorry, can't edit it anymore)

With presage, Whisperfish has a high-level Rust library that wraps the official libsignal libraries (which are also written in Rust) and makes it much easier to write clients. The official Signal repo only contains Java/Typescript/Swift wrappers. As presage is rather obscure, I thought that some HN readers might appreciate the link.