1) we ICE/STUN as well as relay for firewall penetration. 2) we use a modified version of version vectors (http://en.wikipedia.org/wiki/Version_vector) and accompanying algorithms to detect and resolve conflicts. In a decentralized system, conflict management boils down to managing causal relationship between distributed updates, and version vector was invented just for that :)

Thank you.

However, having looked at the wikipedia page on Version Vectors it appears that is a protocol for detecting conflicts. I was interested in how you resolve them.

A simple example is a zip file that I add file A to on one computer and later file B to on another computer. When I sync up do I end up with a zip containing no new files, file A, file B, both files or a corrupt zip file. (Does the answer change if the zip file is encrypted?)

I see. There are two categories of conflicts to resolve: meta conflicts (like when you rename a file to "foo" on device A and meanwhile rename it to "bar" on B) and data conflicts (i.e. the example you gave).

We will formally describe meta conflict resolution in a separate post. Because resolution for data conflicts is very application specific, we will publish an API to allow application developers to write their own conflict resolvers. Meanwhile, we will try to provide resolvers for popular file types by default.

From the end user's view, in most cases conflicts are automatically resolved without being noticed. User intervention is required if automatic resolution fails or the user wants to manually merge.

Thank you. That's what I wondered.