The app/plugin will be open source, so you can see what we are doing. Messages will only be sent to the Facebook XMPP server.
On Dec 18, 2013, at 4:24 PM, Jason Goldberg <[email protected]> wrote: > A MITM attack is more than just trusting your SSL cert or Facebook. > > How do we know *you* aren’t secretly intercepting our messages? Does your > platform assume we have to trust *you*? > > On Dec 18, 2013, at 3:36 AM, SafeChat.IM <[email protected]> wrote: > >> Thanks for all the comments so far! >> >>> Is there a reason you did not consider using OTR? Or another of the >>> many secure chat protocols? >> >> >> We did not want to use OTR, because we do not want to have forward secrecy >> and message deniability. Our idea is to built an encryption scheme that is >> completely transparent to the user, it should not appear different to him if >> he is chatting over an encrypted Facebook chat or not. This way we hope to >> make encryption easier, less of hassle and more mainstream. If we had >> session keys that expire after the conversation is over, the user wouldn't >> be able to read the messages later on (or on a different device) or send >> offline messages (all things possible with original Facebook Messenger). >> >>> What safeguards do you have against a MITM attack? >> >> >> We were thinking to query the public key server over HTTPS and validate the >> certificate (either through a CA or hard coded in the plugin). Also, >> wouldn't you have to compromise the public key server (to deliver wrong pub >> keys to both parties) and the communication channel to Facebook (to >> intercept the message) at the same time? Therefore, we thought that only >> Facebook itself would have a realistic opportunity for MITM attacks (meaning >> the user would have to trust us, that we don't cooperate with them). >> >> We also thought about building a decentralized Web-of-Trust, but found it >> hard to establish a second secure channel (assuming that users don't >> necessarily engage in real life) without impacting usability. >> _______________________________________________ >> cryptography mailing list >> [email protected] >> http://lists.randombit.net/mailman/listinfo/cryptography _______________________________________________ cryptography mailing list [email protected] http://lists.randombit.net/mailman/listinfo/cryptography
