Could you give a TL;DR for that PDF paper.
(And also put that TL;DR in your original post. Scanning through 6 pages of a technical whitepaper without knowing what to expect in it is no fun)
A sybil attack is someone creating false identities to overcome trust in a DHT/p2p network, this paper describes a method to counter that with social links:
3.2 A simple sublinear protocol -
http://imgur.com/BCWJW8cHowever, I don't even know that this is needed. As we are building a trading network, one could simply offer escrow services on the network as items of trade and it would automatically allow trusted agents with reputation.
Also, let me know what would be the pros and cons of using Bitmessage for the messaging layer in your proposed system?
I can just say that I haven't found any obvious cons with using Bitmessage as the messaging foundation, that's why I am looking for comments.