Wouldn’t call it concern. Rather further research.
[quote]I am still curious to see setups with just one hidden service as server and a client[/quote]This is in fact possible. Instead of using ocat address.onion you would replace address.onion with a parameter -R to run as a ‘client’ only mode. That means only one out of the two parties has to go through configuring a HS. Bear in mind though that contact can only be established after the client party connects to the one running a HS, becuase the latter can accept incoming connections while the former cannot.
I forgot to add, I meant also without using onioncat. Because that adds complexity and makes the setup more difficult.
For example by using a Tor hidden service mumble (TCP mode) server + Tor client connecting to it (also in TCP mode).
Advantages:
- onioncat not required
- just one hidden service required rather than two (better latency)
Or some Voip client using TCP. Just saw that linphone has a SIP TCP mode. Someone could set up a Tor hidden voip server and the calling partner could connect to it through Tor in TCP mode. Advantages:
- onioncat not required
- just one hidden service required rather than two (better latency)
The only reason clearnet is pursued is for those who want to contact a non-anonymous party.Not necessarily.
Its unlikely that first contact ever be initiated through VOIP.Didn't had first contact in mind. Unrelated to my argument.
[quote]The latter would have to include, that the server can long nothing useful, just notice, that two random pseudonyms have an encrypted voice chat. [/quote]If the two sides are anonymous, then usage within the Tor network makes more sense.
Not necessarily. Two Tor users having a voice chat using a clearnet server can make sense. Conditions:
- ignoring the ZRTP fingerprinting issue below [if it’s valid, then the two Tor users and a clearnet server should of course not be used - but I would like to explain my thinking here]
- two Tor users know each other already, met offline, agreed to meet up on some public free clearnet voice chat server (or perhaps they’re using TorChat or something like that and agree on the server)
- no hidden services involved (best latency using Tor)
- random pseudonyms
- voice chat client that supports TCP mode
- voice chat client supports end-to-end encryption
- see also: Voice over IP (VoIP) (I wanted to say the same there.)
When using zRTP + SRTP for encryption in any stretch that goes on the clearnet, be sure to never select a VBR (variable bitrate) codec as the pauses in a conversations produce fingerprints in the encrypted stream that allow the adversary to infer what words are being said.This sounds horrible. Sounds like a complete failure of ZTRP. Should be documented. Please add this + reference to the https://www.whonix.org/wiki/Voip wiki page. In that case probably my above use case Tor users having a voice chat using a clearnet server should be avoided and one hidden service should always be involved.