Looks like the same design crispweed over on BTT came up with (and implemented) back in May: https://bitcointalk.org/index.php?topic=628547.0

So is this "withdraw_password_type" tx already in BitShares and working? Theoretically we could do a BTSX to SwapBill trade as a test?

Hi there!

Yes, this is the same algorithm as is used for cross chain exchange in SwapBill.

You can find some more discussion about this on this blog post:
http://upcoder.com/11/atomic-cross-chain-exchange/

The key point, I think, is to try and standardise on a good secret hashing function.

SwapBill is currently *live* on the bitcoin and litecoin testnets, and yes, it would be very cool if you want to try out exchanges against this.

Just shout if you need some help setting this up..