[OTR-dev] /me bug

[Thijs Alkemade]

On 10 sep. 2013, at 20:02, Jurre van Bergen <drwhax at 2600nl.net> wrote:

> 
> Signed PGP part
> On 09/10/2013 07:46 PM, Jacob Appelbaum wrote:
> > Heya,
> >
> > There exists an information leak in Pidgin/Pidgin-OTR where Pidgin
> > doesn't allow Pidgin-OTR to encrypt a specific message before it is sent
> > to the network. Specifically on IRC networks, users who emote through
> > the use of a message such as `/me thinks this is a bug` - will leak the
> > full text of their /me command.
> >
> > This is annoying and it would be nice if Pidgin didn't treat /me
> > messages in this way. It appears that around the same time as learning
> > about this bug, I found a bug report with a fix for Pidgin itself.
> >
> > If there are any Pidgin/Pidgin-OTR users on this list who also use IRC
> > with Pidgin, it would be great to see if the following patch fixes the
> > behavior of /me on irc:
> >
> >   https://developer.pidgin.im/ticket/15750
> >
> > This could also be fixed inside of Pidgin-otr - though I think the right
> > place is inside of Pidgin itself. It would be useful if IRC using
> > Pidgin-OTR developers could test the patch attached to ticket 15750 on
> > the Pidgin bug tracker.
> >
> > Useful questions to answer:
> >
> > Does it solve the /me info leak for you? Does it cause any adverse
> > issues? Does it make sense to put this into Pidgin-OTR?
> >
> > All the best,
> > Jake
> >
> 
> I tested this patch a few weeks ago and it doesn't fix the current issue
> in IRC while being in an OTR conversation.
> 
> Jurre

Hello,

I'm the author of that patch. One thing to note about it is that it doesn't
fix the decryption: If you send "/me nods." from Pidgin to Pidgin, the
receiver will see it as "\001ACTION nods.\001" (or whatever weird characters
GTK uses to render \001).

The possible solutions for that would be:

- Pidgin-OTR passes a decrypted message to back irc_parse_ctcp() to be handled
like normal CTCPs. That would be a bit of a hack, as I don't think Pidgin-OTR
currently needs to differentiate between different protocols like that and
this would create a hard dependency between Pidgin-OTR and the IRC prpl.

- Pidgin-OTR replaces all occurances of "\001ACTION foo.\001" with "/me foo."
when decrypting. This is not a pretty solution either, but at least it would
not create a dependency of Pidgin-OTR on the IRC prpl.

- Pidgin-OTR uses different libpurple signals. For example by hooking "irc-
receiving-text" and "irc-sending-text" it would be possible to encrypt every
CTCP (including ACTION) and decrypt them while maintaining the handling for
them by libpurple. Downside of this is that Pidgin-OTR needs to be able to
parse and generate IRC PRIVMSGs.

The last one would also make this patch unnecessary.

I have not been able to reproduce the problem Jurre had with my patch. Using
Pidgin on Wheezy with my patch I've verified with Wireshark that everything
is encrypted when sending "/me".

Regards,
Thijs

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 841 bytes
Desc: Message signed with OpenPGP using GPGMail
URL: <http://lists.cypherpunks.ca/pipermail/otr-dev/attachments/20130910/da0e78db/attachment.pgp>