Security issue: it isn't at all clear to me what "trust" means here. In
something like GPG or SSL, the trusted assertion is "the key whose
fingerprint is ...63c7cc90 is controlled by 'Simon McVittie
<simon.mcvit...@collabora.co.uk>'" or "the key whose fingerprint is ...
is controlled by the administrators of bugs.freedesktop.org" - it binds
a key to a somewhat human-comprehensible identity (name and email
address, or domain name). I would have automatically assumed that the
same was true in OTR - binding a key fingerprint to a JID (or whatever
else the identifier is, in non-XMPP protocols) - but that doesn't seem
to be happening here. Instead, we're saying "I trust this fingerprint"
but it isn't clear what property of the fingerprint we're trusting. In
particular, we don't seem to be binding a fingerprint to a JID.

Concretely, suppose I talk to xavier.claess...@collabora.co.uk and you
present key ID 12345678 [1]. I verify out-of-band that that is really
your key ID (perhaps by phoning you or receiving GPG-signed email) and
mark it as trusted. Next, I talk to guillaume.desmot...@collabora.co.uk
who presents key ID fedcba98, and again, I mark it as trusted. Now
Guillaume hijacks your XMPP account, and when I next try to talk to you,
Guillaume presents key ID fedcba98. I have "trusted" that key, so my UI
doesn't indicate that anything is wrong - but it isn't your key, it's
Guillaume's!

How does OTR typically deal with this situation? Do OTR users memorize
key IDs and ignore the JIDs and contact names presented by the UI, or
does the Pidgin OTR plugin store pairs (JID, key ID) and warn the user
if an unexpected pairing is found, or does "trust" here mean "I trust
this person not to impersonate any of my other contacts"?

[1] in real life the key ID would be longer than that, but you get the
idea

-- 
You received this bug notification because you are a member of Desktop
Packages, which is subscribed to empathy in Ubuntu.
https://bugs.launchpad.net/bugs/296867

Title:
  empathy needs to support OTR encryption

Status in Chat app, and Telepathy user interface:
  Confirmed
Status in One Hundred Papercuts:
  Invalid
Status in Telepathy framework - library:
  Confirmed
Status in “empathy” package in Ubuntu:
  Triaged
Status in “libtelepathy” package in Ubuntu:
  Confirmed
Status in “empathy” package in Fedora:
  Won't Fix

Bug description:
  Binary package hint: empathy

  Hello, 
  I just tried empathy (the Intrepid version) and it looked very solid and 
stable. There were a few minor things that could be improved (e.g. 
automatically resizing the contact list), but that is not the topic here.
  The reason why I won't switch to empathy from pidgin is the missing OTR 
support (http://www.cypherpunks.ca/otr/ ). This is a really important feature 
because no one should read your messages.
  There were others with the same idea (links at the bottom).
  Would be so great if it could support that important encryption standard.
  Thanks for helping out!

  Links:
  https://bugs.launchpad.net/ubuntu/+source/empathy/+bug/253452/comments/2
  http://lists.cypherpunks.ca/pipermail/otr-users/2008-September/001479.html
  http://bugs.freedesktop.org/show_bug.cgi?id=16891

To manage notifications about this bug go to:
https://bugs.launchpad.net/empathy/+bug/296867/+subscriptions

-- 
Mailing list: https://launchpad.net/~desktop-packages
Post to     : desktop-packages@lists.launchpad.net
Unsubscribe : https://launchpad.net/~desktop-packages
More help   : https://help.launchpad.net/ListHelp

Reply via email to