Ooh. Not sure what kind of validation errors you're seeing, but it looks like this is the code that calculates message ids in Habitat and Tilde Friends, and my brain is mush right now, but they don't look equivalent to me:

• https://tildegit.org/jeremylist/habitat/src/commit/d1fa78aa71a767c326b1811e3cde48ae0ff54184/src/SignJSON.cpp#L76
• https://dev.tildefriends.net/cory/tildefriends/src/commit/9b00b41a1eeaf5a1b9ab6c2fc78b3a0d00043c5b/src/ssb.c#L989