XSF Discussion - 2019-02-27

hi

another question about OMEMO :) If I understand the XEP right one should encrypt the key and the GCM tag. Looking at dinos implementation it only seems to encrypt the key not the tag. Whats right?

Interesting catch, I'm curious how dino is even able to talk to the other clients then

Pretty sure encrypting the tag is the right way and all other clients do so as well

jubalh, do you have a link/pointer to the relevant part of dino's implementation?

Well, I'm not totally sure about it, but I think its this: https://github.com/dino/dino/blob/6de86c2733a26eb5034087ab25205ba1cba1e279/plugins/omemo/src/trust_manager.vala#L73

Syndace, flow ^

jubalh: Are you talking about "add_encryption_tag_to_message"?

In line 153?

which appears to be just the EME extension element (/tag)

ahh so it does get encrypted?

too many xeps to read :)

Syndace, but thats not the gcm tag right?

Syndace, no, it is a tag in the sense of XML

Tag means XML-Tag there, it's just a little confusion

err, jubalh ^

so the gcm tag isnt encrypted if i see it right

jubalh, flow: This behavior changed in OMEMO. The original version would put the gcm tag to the ciphertext (this way it doesn't qualify for authenticity, but at least as a checksum), later the behavior was changed to encrypt the gcm tag to each device (so we get real authenticity as the per-device encryption is also signed). All clients support decrypting the old version, but for some time, some clients lacked support for decrypting the new version. Dino support decrypting both, but still encrypts using the old protocol. We should definitely change to the new version and there already is an issue for it https://github.com/dino/dino/issues/514 ;)

l, awesome thanks for clarifying this!

l, anywhere I can read up on the details? I have the same problem that my lib works with all clients but Dino.

Hello, I've got a question about "OTR has widely been replaced by OMEMO in the XMPP network and is recommended to be used instead." that is on https://wiki.xmpp.org/web/OTR It seems it's not clear what is recommended there and I think some draw the conclusion that it's OTR that is recommended (see: https://github.com/golang/go/issues/30141#issuecomment-467913000 ). I'm not a native speaker but what do you think about improving it so that the intent is clear?

"OTR is no longer the recommended way to wreck your user experience in return for some badly-understood security. Use OMEMO instead"?

dwd, +1

that

dwd, 👍️. sounds unambiguous

just to show you the context: quote "in the XMPP world, the OTR protocol is still used as the standard secure messaging protocol" on https://github.com/golang/go/issues/30141#issuecomment-462031961

[Redirect to:OMEMO]

Wiktor, http://omemo.top/

I know I know, but apparently some people don't, I already commented on the GH ticket but the OTR guys took the quote from XMPP wiki as a recommendation *for* OTR

that's... I think... sub-optimal

Wiktor, don’t you have +w on the wiki?

oh, wait, I do have it 🤔️ I hope it doesn't look weird if I say "even XMPP wiki recomends" and then write the recommendation myself :)

hah

just put dwds suggestion in it

👍️

That golang issue is missing the transport agnostic use-case, which is not inexistant. (even if that's what's mostly criticized of OTR in the XMPP community)

yeah, I was just annoyed at taking XMPP as an example of OTR being successfully deployed

I still use and prefer OTR over OMEMO

I'm sure OTR is still in use in some circles

I don't mind their work, it would be completely stupid if I dictated how they should spend their time :)

Like those serrvers that mandate OTR

jonas’, why? genuinely curious

Me too

Wiktor, mine and my wife’s primary 1:1 client doesn’t support OMEMO in any usable way (i.e. without compiling some modules which aren’t even working)

while OTR was painless to install and to use -- except with Conversations, but *that* issue has resolved itself nicely.

jonas’, what's that client that your wife is using?

pidgin

got it

in the past because multi-protocol, and now because "used to it"

and why change a running system

in a single-client setup, it’s very much "good enough"

especially when you’re still from the age of ICQ, so you know that a sudden reconnect causes lost messages and you need to negotiate that in-band

no probs with that, I understand legacy solutions, heck, I'm still using some ;)

I personally still use pidgin to keep the pain levels high enough to motivate me to work on my own client side stuff

haha, good idea 👍️