Using Gajim Instead of Pidgin for More Secure OTR Chat
If you don’t know about OTR, it’s awesome. It lets you have end-to-end encrypted chat sessions with people so that only you and the person you’re chatting with can read the chat messages and all other parties—such as your chat server (often Google), your ISP, or anyone else eavesdropping on your—cannot. It also has cool features like forward secrecy that other cryptosystems like PGP don’t have. If you’ve ever been to a CryptoParty, setting up Pidgin and OTR and learning how to verify keys is always on the schedule.
As awesome as it is, Pidgin and the Pidgin OTR plugin have problems. They rely on the libraries libpurple, libotr and libxml which are massive, written in C/C++, and are littered with memory corruption bugs. In 2011 EFF started the Open Source Security Auditing project and fixed several bugs in Pidgin-related libraries, but that project was far from complete. Just look at Pidgin’s security advisory page to see how often Pidgin security bugs get fixed. It’s great that bugs are actively getting fixed in software that experts recommend activists to use, but who knows how many more bugs haven’t been reported to the developers and are actively in use compromising the computers of people who put in extra work to remain secure.
I recently discovered Gajim, a jabber client written in python. Gajim also has an OTR plugin, but rather than depending on the bug-riddled libotr it uses an implementation of OTR written completely in python with no C bindings.
Writing programs in Python is a lot safer than writing them in C. With python, developers don’t get direct access to allocate, overwrite, and free memory. Instead they just declare variables and the python interpreter and it’s garbage collector take care of the messy memory management logic. This means that bugs in a python implementation of jabber and OTR are less likely to lead to arbitrary code execution.
If someone sends you a malicious message that triggers a bug in Gajim or it’s OTR plugin, they’re much more likely to just crash the program than to take over your computer.
That said, I noticed that Gajim’s Wikipedia page says:
Despite being written in Python (and thus generally invulnerable to buffer overflow attacks), Gajim has a history of a critical vulnerabilities. Up until late 2011, it was possible to forge a link such that when a receiving Gajim user clicks on it, arbitrary code would be executed on the Gajim user’s machine.
As far as I know there hasn’t been a formal code review of Gajim. Just because there used to be an arbitrary code execution bug (that’s since been fixed) doesn’t mean that the project as a whole suffers from security problems.
I’ve only been using Gajim for two days now, but so far it seems great. After installing Gajim you need to click Edit, Plugins, and switch to the Available tab. From there you can download and install the Off-the-Record plugin. Back on the Installed tab you can click Configure to generate OTR keys for your accounts.
I haven’t looked in detail at the plugin installation mechanism for Gajim, so I don’t know if the download goes over HTTPS, or if the package is signed. I hope that both are true, but it’s quite possible that neither is.
Of course, when Windows users download Pidgin’s OTR plugin from cypherpunks.ca, it’s never been over HTTPS and has never forced signature verification either. We need to work in this.
I generated a new OTR key when I started using Gajim. But since I’ve already verified OTR keys with dozens of people, and my OTR finerprint is even printed on my business card, I wanted to keep my old OTR key.
So I decided to write a Pidgin to Gajim conversion script called pidgin2gajim. If you too want to switch to Gajim but don’t want to give up your existing OTR key, hopefully this will be helpful.
Update: After talking to some people it appears that libotr isn’t as bug-ridden as the other libraries that Pidgin depends on, libpurple and libxml2. I’m still glad there’s a native python implementation of OTR though.
Legacy comments, imported from previous version of this blog:
I have the "Plugin Installer" plugin installed for updates over FTP and configured it to "use TLS transport" and with Wireshark i could see that they are using ProFTPd with TLS
Someone should refactor Gajim Plugin Manager to use HTTP, instead of FTP, so proxy, such as Tor, would be useful.
Have been using gajim for a while after you suggestion. Two major concerns:
- Logs cannot be completely deactivated - start and stop of each otr session are recorded. This is a serious issue to plausible deniability. Bug report: https://trac.gajim.org/ticket/7953
- When running in Windows 7, shutting down the computer causes incorrect shutdown of gajim. At restart, all gajim settings (accounts etc.) are lost.
So I am returning to pidgin for now.
What about jit.si as compared to Gajim? Any experience or thoughts?
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What's the current state of OTR chat clients under linux? Is gajim still good to use, or are there better things out there?
Nowadays I'm using Tor Messenger: https://blog.torproject.org/blog/tor-messenger-beta-chat-over-tor-easily
Actually, Tor Messenger just ended support for it in March 2018 and it is therefore NOT recommended to use Tor Messenger anymore. So what now? is gajim the only safest option for xmpp? Would appreciate your reply on this
I use xmpp way less frequently than I used to, but I'm pretty fond of CoyIM: https://coy.im/
It's nice, minimalist, and implemented in golang. Though unfortunately it lacks a few features I like, like OTR authentication options that aren't just verified fingerprints (shared secret, question/answer, etc).
Regarding to your reply, Micah, do you still recommend Gajim over Pidgin? do you find CoyIM better?
Anyway, I leave Skype some time ago and I am looking for an alternative, and I was thinking about use Wire or Jitsi. I research a LOT about both IM programs (and lots of others) but I just wanned to know what's your opinion/recomendation on this mather since you use both of them.
I read lots of nice things about Wire and now its fully open source and has been audited but I read that it collects many metadata. Also it stores the contacts list at their servers: https://motherboard.vice.com/en_us/article/gvzw5x/secure-messaging-app-wire-stores-everyone-youve-ever-contacted-in-plain-text
On other hand, all the funcionality that Jitsi has looks amazing,. My only concern about it's the lack of public audit and some minor privacy issues you spoke about in its public lists some time ago (the part about conecting to third parties like Google Analitycs and Gravatar (wich I think is optional).
Alternatively, Ring and Riot.im are quite interesting too, but they are still immature projects.
Presumably it relies on libxml2 for handling XMPP at some point, right? :]
Actually it doesn't look like it. At least, libxml2 isn't a dependency.
[micah@spock] ~$ apt-cache show gajim
Maintainer: Yann Leboulanger
Writing programs in Python is a lot safer than writing them in C? Not true. Python has eval, so there is your arbitrary code execution. (There seem to be people who try to write calculator web apps using eval, which is a bad idea.) Python programs need to abstain from eval (and probably a few other features as well) in order to be safe. This seems to be given for gajim-otr, though.
I have use Jitsi a lot and works perfect.