Shared secrets are simple to understand and simple to use, but they're often A Very Bad Thing when it comes to good security, in part because secret distribution is not easily done in a safe way. It is very unpleasant to clean up after one participant's copy of the shared secret key is exposed to the wrong people, whether deliberately or accidentally. For example, if 10 different people are sharing a collection of files via BitTorrent Sync and one of those people lose their laptop to a thief, the remaining 9 have to quickly change that secret key to a new one they all agree upon. There isn't always a safe way to exchange that new secret quickly. What I really want to see is support for public/private SSH-like keys as an optional alternative to the shared secret key solution. Folks who don't understand how to use such keys don't have to use that option. In the above scenario then, the remaining 9 users will simply delete the public key from their systems that belongs to the compromised 10th person - no new secret key has to be devised and distributed.