9.1-9.4

1. Why would you sign something that you didn't know the contents of? This is not incredulity about the actions of the uninformed, but rather, under what circumstances would you sign something that you didn't know the contents of? Does it involve some notion of trust, whether it be a chain or hierarchy of trust or a certificate authority?

2. The overview given of how to alter a contract to obtain 2^30 variations was (understandably) simplistic. In reality, many file formats allow arbitrary data to be stored somewhere within, and there is certainly not a one-to-one correspondence between representations and the information required to store them. I suppose either party could inject random garbage into a file in such a way that the stream was still a valid sequence in the language. This may not address the problem directly, though. The issue, as I see it, is that in a contract, both parties need verification that the same contract is being signed. In the physical world, this can mean temporal and/or spatial proximity, but it may be possible with an escrow or arbiter or some other trusted third party. Or maybe it's a simple problem and I just don't see it.