@metaweta: The technical side is interesting, but seems like the admin side would be too; how did the administration and contract side play out?

Someone needed to front an estimated $100k of GPU costs, without being sure it would work - and then pay for your work on top; who risked that? You had no proof the claimed Bitcoins inside were real, or as many as claimed. You're in New Zealand(?) and the customer is in Russia - you need the file to study it and if you crack it then you have the Bitcoins as well - how did they become comfortable that you wouldn't steal them and say you couldn't crack it? Did it worry you that the owner might not be able to convert them to cash, e.g. if the Exchange was shady and there was very little recourse?

How much work did it take to convince your partner to stop what they were doing, and write GPU code for a crack which might not work?