[Bitcoin-development] [PULL] Add scriptPubKey enforced sendescrow and redeemescrow API calls

[bgroff at lavabit.com]

Gavin wrote:

> It would be spiffy to publish a new type of bitcoin address that is an
> "m of n address", that anybody could pay into, but would require m of
> n signatures to spend.  Publishing a really really long address with
> all n public keys would work.

Here's a strawman use-case for a browser centric flow for a 2-of-3 scenario.

Funding:

* User is on Merchant site on the checkout page
* User selects a transaction Observer (I'm trying to get away from using
the word escrow, because the funds are not held by the third party)
* Merchant redirects to the Observer, passing in the Merchant's payout
address
* The User enters User's address
* Observer presents multisign address
"2,merchant-addr,user-addr,observer-addr" and terms and conditions - i.e.
under what circumstances the Observer will sign
* User copy/pastes the multisign address to their bitcoin client and sends
funds
* After some blocks go by, merchant ships

Redemption:

* Merchant reminds User to release funds
* User creates a partial tx paying out to merchant-addr and emails or
copy-pastes to Merchant
* Merchant signs and publishes the tx

Funding requires two pastes and redemption requires one.  A browser
plug-in would reduce the User effort to a couple of confirmatory clicks -
"do you want to send X BTC to Merchant Y with Observer Z?" and "do you
want to release X BTC to Merchant Y?".

--
Bobby Groff