Quote from: WorldOfBitcoin on October 09, 2012, 06:30:08 PM

what applications have you seen this in use? I more interested in eCommerence examples rather then anonymous messaging.

The blockchain is a horrible place for that.

Quote from: WorldOfBitcoin on October 09, 2012, 06:30:08 PM

ig user A sends bitcoin to B. However C says it was his payment and contests transaction with B. If there was a handshake between A and B could add security.

The latest on that is:

Quote from: Gavin Andresen on September 10, 2012, 12:22:11 AM

We need a payment protocol with non-repudiation built in.

See https://gist.github.com/2217885 for a multisig version (the singlesig version is simpler, but the merchant <-> customer communication will be the same).

and here:

[Bitcoin-development] Payment protocol thoughts
- http://sourceforge.net/mailarchive/forum.php?thread_name=CAAS2fgQN0zpbA4X276hs3dLR%3D_vX6Q5%3DAnHcquy1zpneu4zG2w%40mail.gmail.com&forum_name=bitcoin-development