[whispersystems] big signal groups and performance

[Ruben Pollan]

AFAIK signal groups are 1:1 encrypted, that means that signal has to encrypt to
each of the addressees. I guess this could be a performance problem for big
groups, as it could drain the battery of the device having to encrypt for many
recipients.

Is there any measurement on what could be the upper limit for signal groups?
How big are the big groups around?

[Johan Wevers]

Post by Ruben Pollan
AFAIK signal groups are 1:1 encrypted, that means that signal has to encrypt to
each of the addressees. I guess this could be a performance problem for big
groups, as it could drain the battery of the device having to encrypt for many
recipients.

Usually in such cases only the session key is encrypted with each public
key. That isn't much data, even for a group with 1000 members.

[agrajaghh]

have a look at the described optimizations at the end of this post:
(heading: The TextSecure Group Protocol)
https://whispersystems.org/blog/private-groups/

afaik they are not yet implemented, am I right?

Post by Johan Wevers
Usually in such cases only the session key is encrypted with each public
key. That isn't much data, even for a group with 1000 members.

[Ruben Pollan]

Quoting agrajaghh (2015-11-19 22:24:00)

Post by agrajaghh
(heading: The TextSecure Group Protocol)
https://whispersystems.org/blog/private-groups/
afaik they are not yet implemented, am I right?

Post by Johan Wevers
Usually in such cases only the session key is encrypted with each public
key. That isn't much data, even for a group with 1000 members.

Thanks for the replies, I readed this blog post when was posted but it seems I
forget about it. Encrypting only the session key looks fine to scale.