Empty group messages after RSA key renewal

ChristianeMussmacher commented 7 years ago

Bug only reproducible on iOS clients

Situation

Android or iOS client opens group (admin)
adds Android and iOS clients to group
members join group
iOS client changes RSA key
from this moment on, iOS client is not able to receive messages in group chat (empty messages)

--> We tested the same scenario with iOS only and Android only groups. After changing the RSA key on either an admin device or an member client, no problems were observed.

--> Bug is only triggered when both, Android and iOS clients, are members a group where iOS group member renews RSA key pair.

Closely related to: #813

pavel-mayer commented 7 years ago

Problem is caused by a bug in the Android client. In the getEncryptedGroupKeys() there was no check for the requested id of the public key, so an Android client might generate encrypted group keys for an old public key, but the server would assume they are using the new key.

pavel-mayer commented 7 years ago

The cause was actually a bug in the Android client fixed here hoccer/hoccer-talk-spike@1624a798ea24a0a92870e8ca60fde6e47caa5bb6

It also needs a fix on the server that should also fix other group key problems: hoccer/hoccer-talk-spike@722eb6b84c45c48f37e6226b888ca52517a2bde8

hoccer / hoccer-xo-iphone

Empty group messages after RSA key renewal #819