Multi Sig Escrow System HELP

[Barrack Obama]

Hello guys,

I am in the works of creating a bitcoin auction site.

I'm having a lot of trouble understanding how to make a multi signature escrow system.

Heres what Im looking for:

When a user wants to purchase item he has to pay 1% commision fee then he sends his bitcoins to a escrow address. I want there to be 3 possible signatures, with two being enough to send the payment through to the vendor.

The buyer gets 1 signature, the vendor gets 1 signature, and we get 1 signature.

Are there wallets that support this?

Does a system like this already exist?

Would anyone be interested in building one, or explaining to me how to do it for some Bitcoins?

Appreciate it!

[monsterer]

The problem you will have with this is that the majority of people can't send coins to a multi-signature address because they're using blockchain.info, or some other 3rd party wallet which doesn't have support for multi-sig.

I know this because I created a game which handed out multi-sig addresses to its users and no one was able to deposit. I had to move over to a different system until the support for multi-sig gets better.

Cheers, Paul.

[fbueller]

I've written out something that can be used on the server side, it's in PHP. https://github.com/Bit-Wasp/multisig and the demo is http://multisig.thomaskerin.tk / http://multisigtestnet.thomaskerin.tk

I've added an electrum library to there, because you should deterministically generate your sites keys from a master public key, and keep the seed on another computer. But the code currently just creates a new keypair, imports it to bitcoind immediately in the mean time. This is only really because in the code, so they only need to sign once on top of the sites signature.

Sending to P2SH addresses is a problem - users will probably have to use bitcoind/qt or electrum. So is signing, but https://coinb.in/multisig will do all that for you in a nice way.