Good points, Sandy. However... (student dunce cap stapled firmly to my head [ouch]) First of all, it's not clear to me that it is impossible to structure the deal so that your escrow service even knows that it is a murder contract. It might be possible to construct it as "I authorize you to pay the other party if they can produce a certificate that, when decrypted with this key, produces this text." The production of that certificate might only be accomplished through the cooperation of the on-line coroner -- see scenario two below.
SCENARIO ONE
I set up a meat-and-potatoes escrow business. I keep my nose clean. I honor my obligations. I build up a good reputation. At some point, I'll be approached by a murderer and the person who is hiring him or her. I'll accept the payment. When the murder is committed, I won't pay off. The murderer will (a) sue me (I don't think so), (b) damage my reputation (I'll leave this one as an exercise for the student), or (c) murder *me*
Why can't I damage your reputation? Assuming: a) there exists a public place to cast aspersions on your business b) that I have a receipt digitally signed by you indicating that you accepted the payment and contract from the two parties c) that I can prove I have "executed" my end of the bargain (pun intended) How will you defend yourself? I'll simply challenge you to produce the receipt (signed by me) proving that I received the payment from you, which - obviously - you won't be able to do. Your only recourse is to ignore me and hope that no one else listens to me (might work once but ...). I don't see why the subject of the contract would ever come up. (And surely, you wouldn't try to argue that you didn't pay me simply because the contract was for murder -- I don't think your potential future clients would relish giving their escrow service the power to judge the moral virtue of their contracts.)
SCENARIO TWO
I set up a phoney murder-for-hire business. Someone contracts with me to bump-off their rich uncle. The client deposits my payment with a reputable escrow company, "Murder Escrows R Us." I go to the uncle and tell him the whole deal. Using digital technology, bribed coroners, etc., we fake his death. When the news hits the Net, the escrow pays me off. The uncle comes back to life, disinherits whomever he suspects wanted him dead. And I laugh all the way to the digital bank. I create a new pseudonym, place another murder-for-hire ad, and do it all again. Given our Brave New World, nobody can touch me.
Here's the real problem: How can I (as the hypothetical murderer) prove to the satisfaction of the hiring party and the escrow service that I have fulfilled my part of the contract? It seems that, in order for this scheme to work, the coroner must be in the business of regularly publishing signed and certified death certificates on the net. Otherwise, a premise of the whole scenario (that there is a way for me [the killer] to prove that I have done the deed) is not fulfilled and we would never have made our "anonymous" contract in the first place. So, the coroner (the death-certifying agent) is in a position of considerable trust. And after all, "Murder Escrows R Us" is not the only company making use of the coroner's death certificates; Net Life Assurance Corporation ("Get Net, it pays" :-) will also base its (potentially quite-large) payoffs on the certificates issued by the coroner. I'm assuming therefore that the life insurance companies and the like will exert sufficiently strong influence to ensure that your scenario is extremely unlikely. Perhaps the CyberNation Association of Life Insurance Companies has promised to hunt down and shoot like a dog any coroner they find out has faked a death certificate. Or, perhaps you must put up a very large bond before you become established as a coroner who is trusted to issue net-death certificates. In either case, the problem boils down to this: Everyone has their price; can I, as the hired killer, afford the coroner's price? I'm betting that the coroner's price is pretty damn high. [The murder victim could presumably help with the bribe payment too, but once you've told him about the murder plan, he can take steps to protect himself from you and there will be little motivation for him to help.] (Now how do I get this thing off my head ...) -- Jeff