This
https://www.crowex.com/static/digconapp/crowex_protocol.pdf is a protocol based on this
https://en.bitcoin.it/wiki/User:Casascius/Escrow_scheme_draft entry in the bitcoin wiki.
We’ve built a web app (
www.crowex.com) for negotiating 2 of 3 type escrow contracts and we’ve used the above protocol to incorporate a threshold scheme. It is a slightly different approach to using threshold signatures.
I believe in order for this to be a verifiable secret sharing scheme it would technically still require that the two parties in the transaction have direct communication with each other and not through the server. However, by using ECDH we are able to avoid the server being party to certain information and the parties can communicate directly, out of band, if they wish to verify their public keys.
I’ve posted the protocol here in case there are any technical questions/comments.
