Uhh, Jitsi? Jitsi Meet? Free and open source of course.
Jitsi has ZRTP encryption. Jitsi Meet uses WebRTC and its encryption isn't the same, but from the academic research papers I've read such as "Stegozoa: Enhancing WebRTC Covert Channels with Video Steganography for Internet Censorship Circumvention" from June 2022, it's convincing enough for me to have set up my own Jitsi Meet server on a Debian Linux Virtualbox machine.
From the paper:
"Given that the peer-to-peer connections carrying the video
streams are encrypted end-to-end, not even a state-level adversary
with unrestricted access to the network infrastructure will be able
to observe the raw video content of the WebRTC streams. "
XMPP/Jabber with OMEMO encryption, it runs on federating servers.
Session is a fork of signal that doesn't require phone numbers, there's some cryptocurrency something or other in there I don't quite get, but I don't believe you need it to send messages.
There's Tox, another p2p sort of thing.
Then there's threema, wire, and a bunch of others im not all that familiar with.
> Session is a fork of signal that doesn't require phone numbers, there's some cryptocurrency something or other in there I don't quite get, but I don't believe you need it to send messages.
This is not a fork of Signal. It was originally designed to use Signal protocol under the hood for encryption and key management but does not anymore[1]. They appear to be going a different direction now with the service using cryptocurrency nodes to route the service[2]
There are a few secure alternatives but as stated in the article, their goal is privacy as well as security. For instance they don’t even know who’s in which groups or that a group exists and they keep as little metadata as possible. The remaining metadata that is required for the service to work, they encrypt and don’t even have the keys.
What metadata does signal leak? They have sealed sender since 2018 which means the most interesting metadata isn’t shared. Just don’t share contacts and register with a disposable number.
Widely used? No. I've found Session to be a decent alternative however it's still early development which entails some scuff and details as to how they intend for it to be financially supported long term aren't clear.
TLDR on Session is that it's a fork of Signal (effectively same front end, key scheme, encryption scheme, etc) with a modified transport/delivery and notification system and without the phone-number-as-an-identifier caveat that signal has.
Note: Sorry for the wall of text below.
As for what that modified transport layer is, it's routing all the messaging and data hosting over Oxen (https://oxen.io/) which is a cryptocurrency that serves as a decentralised short term / small size addressable data store and an onion router for those messages/data. As much as cryptocurrency=bad in a lot of cases, here it kinda makes sense as it's just an automated digital marketplace for data hosting and bandwidth with tooling wrapped around it to support privacy and anonymity preserving tools without relying on some hopefully benevolent dictator to run it.
As for who's backing it, same group that develops the Oxen, an Australian non-profit focused on privacy tech and bearing the same name (Oxen Privacy Tech Foundation). While Oxen is pay for use (messaging and all that has an on chain cost), it looks like the foundation is covering the costs of running Session for the foreseeable future. Given the nature of the project, it should eventually be possible for users to pay their own infra costs however that doesn't seem to be implemented yet.
It's pretty easy to use.
1. Install via F-droid or download from the web.
2. Basic cryptocurrency wallet style setup where your account is based on a randomly generated "recovery seed" phrase (string of words with equal bits of randomness as the private key which can be used to rebuild the private key on a new device).
3. Then you can share your "Session ID" which is basically just your public key or you can pay for a custom username which is addressed to your public key (you can set names for contacts after adding them so the username is mostly for ease of discoverability).
4. After that it's basically just Signal but where you can make and throw away accounts at the drop of a hat.
My main complaints are
1. that it's a bit slow on delivery
2. The onion routing half of decentralised storage + routing is still being implemented for Session as the project is very much WIP at this stage.
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My takeaway is that provided it can stick around, Session has potential to shore up where Signal falls short. Give it a year or two in the oven and I might recommend it as a daily driver for messaging.
Likewise for the OPTF and their goals in general. It looks like once Session is "fully implemented" they are looking at trying to expand the approach to a discord/slack/matrix competitor as well which could be interesting. As far as I can tell they are just a bunch of privacy nerds with a little bit of a cryptocurrency lean to them but they are doing good work.
(edit: answering to your initial message, that said that Signal operators also have access to the same metadata, but I guess my comment still answers your sentence "Most important is who when with who which both leak to the server operators" - Signal operators have showed they can't provide this information)
> If you don't store that data or delete it, you can't provide it.
Can I do this easily and still have my homeserver work correctly with Matrix?
Anyway, the law would probably require any operator to keep this data for a while since they have access to it. And I can't rely on my contact's homeservers to delete this data even if they can (technically and legally).
Now, include lower level technical Details such as the IP layer.
1. Imagine you connect to a server to send a message. Now, you send a message to someone else. The server can't see who you are, right? Because the letter misses your name. Imagine someone else sends a message to you.
2. Imagine you to connect to the same server to receive messages that the server stored for delivery with your name on it. The server gives you the messages.
though you will need lotsa RAM for federation if you use synapse (mine keeps bogging down now after a year of mild use (could also be a bug idk, it allocates all the RAM and then nothing goes), now im waiting for the new server software dendrite to be able to migrate from synapse... allthough i wouldnt lose much if i just nuked the synapse instance)
Yes, and I have in the past. But that does not solve the issue completely. If the police asks me some information about one of my contacts, I'll have some metadata stored in my homeserver, and I'll need to hand it over. And vice versa.
It's better that the server does not have access to this information at all in the first place.
I have been wondering how censorship resistant matrix is. As far as I know, groups are not hosted on any particular server, it’s some kind of shared consensus.
I suppose the moderators would still be at risk of hosting platforms and ISPs dropping their homeserver.
If you and everyone you talk to are hosted on servers you trust, down to the physical provider, yes.
EDIT: if the person you're talking to is hosted on Google, Google has all the metadata. Even if one person is hosted on Google and is part of a room you're in, Google has all the metadata in that room.
In 2022 e2ee is the standard for messages but not metadata, and unfortunately Matrix doesn't tackle it, so no, you can't expect 100% privacy.
But the backend of Signal doesn't store who talks to who, so Amazon can't have that information. It also doesn't store what groups exist and who is part of it.
