Publishing New Prekeys

[seanieb]

What are the current best practices around uploading new Prekeys? Should the client poll the server to check if their pre-keys are nearly exhausted, once a day/hourly, on app startup or after a certain number of sessions? Or should the client wait for a server notification that they need to publish.

This was discussed here with respect to libsignal but no solution is mentioned:
signalapp/Signal-Desktop#221

Thanks!

[jrose-signal]

I know the iOS codebase best; here's what it does:

https://github.com/signalapp/Signal-iOS/blob/6ecb00288611f77c39f4f6edb307c986e3709d09/SignalServiceKit/src/Account/TSPreKeyManager.m#L143-L144

That is essentially "check every 12 hours" (the "shouldThrottle" flag is only used for debugging)…

https://github.com/signalapp/Signal-iOS/blob/6ecb00288611f77c39f4f6edb307c986e3709d09/SignalServiceKit/src/Account/RefreshPreKeysOperation.swift#L44-L48

…and "upload when the keys are 2/3 exhausted". There are a number of places that check gets called, not just app startup, in case the app stays resident in memory a long time, but the Signal chat server doesn't today send anything to the client to say you've run out of one-time pre-keys. It certainly could, however.

[edit: hm, not sure why those code snippet permalinks aren't rendering inline]