Be careful with the XMPP - leakage MITM possible : OpSec | Torhoo darknet markets
You can follow any advise on the client XMPP setup but the main issue with the protocol is not your endpoint. The issue is the is the XMPP protocol and related infrastructure.
There are two things you wana conceal:
1. the content of the message (privacy setup),
2. your identity (anonymity setup)
Don't mistake those two please.
Privacy
is ensured on XMPP with the OTR or OMEMO encryption. The issue is that the key exchange in between the communication parties is not foolproof. You both MUST check the fingerprints through a separate secure channel. This is in large scale not practiced. If you don't check it right, the underlying infrastructure of the XMPP allows the adversary to MITM you and read your messages.
Anonymity
is ensured with Tor here. Tor tries to conceal you IP only and nothing more. But Tor, as a low latency network, cannot protect you from revealing your behavioral patterns, your social graph, your login and log out time, the number of messages sent and received at any time, the sender and receiver of the messages, their precise volume and so on from the XMPP server and any adversary that can monitor that server.
Our advice is - don't use XMPP if possible at all and use something more resistant like SImpleX, Briar, CWTCH... and similar solutions that mitigate those leaks and diminish or even make impossible those related attacks from the active as well as passive adversaries.
Fly safe!
Asfaleia Security Consulting
SimpleX in general:
- No user IDs, no identities, therefore not possible to spy on "user" by an adversary. From the design, there is no user.
- unidirectional messages, outgoing messages goes through different channel as the incoming messages
- Incognito mode, for every contact you get in touch with it seems like you are someone else. No social graph available.
- message integrity verification, if the adversary would be able to add a message, SimpleX protocol finds out locally and alerts you
- message mixing, Tor network is a low latency network and an observer can correlate the messages flowing through the Tor network. SimpleX mixes the messages so it is not FIFO but if 5 messages come in the queue it can esily get our of the queue in 2, 5, 1, 4,3 4order, frustrating the timing analysis
- Content padding, where every message is padded to have the same size, frustrating the message size analysis
Briar and CWTCH are pure P2P protocols and while excluding servers from the process, the disadvantages comparing to SimpleX are significant. Both use unique, IDs, don't do any message mixing, no content padding, no incognito mode, no unidirectional messages. It can of course be used but only for specific situations.
post it here, like you know you should (you can crosspost to OpSec too) -> /d/xmpp