Hardware Reference
In-Depth Information
This mechanism is one-way; Gabriel must initiate the protocol in order to fully trust you
as well. This portion of the exchange looks like this:
<root> smp: initiated by gabriel_ice_jabber with question:
"What did I have for lunch yesterday, one word, lowercase?"
<root> smp: respond with otr smp gabriel_ice_jabber <answer>
<jbd> otr smp gabriel_ice_jabber pizza
<root> smp: responding to gabriel_ice_jabber...
<root> smp gabriel_ice_jabber: correct answer, you are
trusted
Congratulations! You have connected and authenticated and may chat away with OTR and
BitlBee! If you are using GTalk and are also logged in to Google with your browser, you
may notice the encrypted messages going back and forth. You can probably log out of
GTalk from your browser, but just for fun, if you are logged in, you will see the OTR mes-
sages, which look like this:
?OTR:AAIDAAAAAAQAAAAFAAAAwBPAdyxNJT7MYxOFBPfmPRCbW3yE6gADfimB7wikaf/
r9/DVQ3hZfJXj+c7HSddySk77fJi3csbRIIxKCSXGLO/
9cOw7SJ+u10d8D6Wp2scCAi7TzO/
YGkZmeGlef3lYUbwaVkH5VoYfLSo+i90McmLrgEfM9kgZuXLtDA1H2f4jWdtBJh1XxdK/
GyZBZvTcncMs/
e3rRrKpSNZiJq0kijMhIK6N4NRdaNK1URipDJai1d2bnGJ2Pk0rihXc5yzCrgAAAAAAAAACAAAAEUw6xZ+tJrdEG/
+yqaiwoDi0Fc9eloiWtIc1UWQ8JTIT3eaKvuMAAAAA.
Understanding the Socialist Millionaire Problem
Even a well-designed protocol such as OTR can have subtle design flaws. For those look-
ing to add cryptography to your project, there is a well-known saying,
don't roll your own
crypto
, which means don't invent your own cryptography because the odds are against you
and one mistake can undermine your security. Plus even seasoned cryptographers don't get
everything right on the first try. Fortunately, releasing the research, design, and code helps
with the peer review process.
In response to some critiques on OTR's authentication phase, the authors improved their
protocol (Alexander 2007). Prior to this paper, OTR users had to verify the fingerprint of
OTR keys out-of-band. While this works, it has a human factor drawback as it is incon-
venient and not very scalable to hand out OTR keys to peoplewith whom you may want to
securely communicate. However, two parties may share more intimate knowledge about
each other that would prove their authenticity.The problem then becomes how do Alice
