A sealed prediction

And another one as backup, because this is Professor Quirrell we're talking about here:

9805a0c7bf3690db25e5753e128085c4191f0114

Obviously, though, this is all misdirection from his real scheme.

It's worth noting, people, that Unnamed joined Less Wrong before Eliezer started writing Methods.

Having said that, it's not clear to me we want to do all this. Sometimes we could be at a game-theoretic advantage by not knowing something. E.g. I don't want to be able to be told that someone's kidnapped my daughter, because then they have no incentive to do so (TDT aside). Maybe Quirrell is actually planning on us being able to verify his honesty.

If Quirrell has a time-turner it seems plausible the time cost required for finding SHA-1 collisions would be irrelevant and the entire method would be insecure.

Nothing as of Jan 2014.

Has now been one year.

So, remember to ask him about it periodically. If it doesn't get revealed in a few months, one can assume he's wrong.

But, Quirrell would understand that if he is wrong, demonstrating that he's willing to admit that would raise his status in this group, and will act accordingly. Indeed, given that it is Quirrell, the hash might even correspond to something he expects not to happen so he can then reveal that he was wrong in a way that not only increases his status but also cause us to underestimate him.

I made a prediction with sha1sum 0000000000000000000000000000000000000000. It's the prediction that sha1sum will be broken. I'll only reveal the exact formulation once I know whether it was true or false.

Someone as clever, powerful, and rich as yourself can likely find a collision if you get to choose both source texts (which is easier than finding a collision with one of the two inputs determined by someone else).

This is actually much harder than you'd think. A hash function is considered broken if any collision is found, but a mere collision is not sufficient; to be useful, a collision must have chosen properties. In the case of md5sum, it is possible to generate collisions between files which differ in a 128-byte aligned block, with the same prefix and suffix. This works well for any file format that is scriptable or de-facto scriptable - wrap the colliding block in a comparison statement, and behave differently depending on its result. However, even for md5sum, it is still impossible to generate a collision between plain-text files with two separate chosen texts; nor is it possible to generate collisions between files that have no random-seeming sections, or that have random sections that are too small, not block-aligned, or are drawn from a constrained alphabet. (Snowyowl's joke would require a preimage attack, which is harder still, and which won't be available at first even if sha1sum is broken, so he will not be able to fulfill his promise to reveal a message with that sha1sum.)

Anyways, since you asked, here are a few more hashes of the same thing. I didn't bother with the SHA3 finalists, since they don't seem to have made convenient command-line utilities yet and I don't want to force people to fiddle too much to verify my hashes.

sha512sum: 85cf46426d025843d6b0f11e3232380c6fac6cae88b66310ee8fbcd3f81722d08b2154c6388ecb1ee9cebc528e0f56e3be7a057cd67531cfda442febe0132418 sha384sum: 400d47bf97b6a3ccd662e0eb1268820c57d10e2a623c3a007b297cc697ed560862dda19b74638f92a3550fbbfe14d485 md5sum: 8fec2109c85f622580e1a78c9cabdab4

It's extremely unlikely that a useful collision exists. The number of short paragraphs in English which make sense and describe a prediction is much, much smaller than the number of SHA1 values. However, if Quirrel's prediction turns out to be very wordy, or comes in a form other than plain text, your suspicion will be confirmed.

A general solution would be something like my archiving setup, which resulted in this page being crawled by the Internet Archive in early 2012: https://web.archive.org/web/*/http://lesswrong.com/r/discussion/lw/421/a_sealed_prediction/