Hi Sarah from Open Privacy / Cwtch team here - the main major difference is that Cwtch servers are completely untrusted under the risk model - they don't learn anything about the groups they are hosting, who is a member of which group, or who each message is for.

The design for groups is still in flux, and they are marked experimental but there are a few more details in our Secure Development Handbook https://docs.openprivacy.ca/cwtch-security-handbook/groups.h...

Metadata resistant group comms is still a fairly large open research problem, and we are also working on the research side to reduce some of the bandwidth requirements that are currently required by our group protocol: https://git.openprivacy.ca/openprivacy/niwl

Interesting project! I've been looking for something to replace Signal, and this scratches an itch.

I see that you're using Tor to route messages? How would mobile devices fair with Tor connections when they go to sleep?

On Android we implement a background service that will wake up periodically and either use the active tor connection or start a new one if the kernel has stopped it for any reason - and also reconnects the UI. This makes Cwtch connections fairly stable on android devices - even for p2p.

However, it also means that Cwtch on Android is fairly battery intensive. We provide a way to easily shutdown Cwtch completely for this reason - and we are researching ways to minimize power consumption (both through tor optimizations and alternative anonymous communication networks)

how will it compare to P2P Matrix?

I'm wondering that too, or specifically how it compares to Matrix run as a Tor hidden service, which is apparently possible:

https://github.com/matrix-org/synapse/issues/2111#issuecomme...

I'm not sure if Cootch is federated, like Matrix, or peer-to-peer. I assume the first, if Tor is being used?

Berry also sounds similar, although it is not released yet: https://berty.tech/

It's Cwtch, pronounced more like Cutch than Cootch

Edit. Cutch was supposed to be more of a phonetic way to pronounce it as opposed to a word with a similar sound.

Really? Intuitively it looks like it should be pronounced "Switch" to me.

Vowels in Welsh are not pronounced like they are in English.

(“Cwtch” is Welsh for “hug”. I know this because there's a good beer called Cwtch.)

One thing the Welsh language is not, is intuitive.

I don't know how either "butch" or "cutch" is pronounced. You might want to offer a common word for people who did not grow up in America...

edit: butcher?

Yes, butch is like butcher but without the "er"

This may help, although I would have thought butch was common enough. E.g. Butch Cassidy and the Sundance Kid

https://www.google.com/search?q=define+butch&oq=define+butch...

Like "clutch" without the "L"?

Close. This is from the homepage:

How do I pronounce Cwtch? Like "kutch", to rhyme with "butch".

In common use you might say "Cwtch in" to mean "snuggle in" or "cuddle in close'

That is a really damn cute name