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Interesting -- how can you verify that f() was applied when by definition you don't know what the output of f() should be? If someone was trying to be dishones
by aquark 15y ago
Interesting -- how can you verify that f() was applied when by definition you don't know what the output of f() should be?
If someone was trying to be dishonest then they could fake any attribute of f() that you could likely verify.
- dexen 15y ago> If someone was trying to be dishonest then they could fake any attribute of f() that you could likely verify. Not necessarily. For example: you can't fake bitcoin transactions, as each one requires significant amount of comuptation. Basically faking would require exactly the same work (modulo problems with SHA1 itself, but that's another matter). This is used for other purposes as well: http://en.wikipedia.org/wiki/Proof_of_work http://en.wikipedia.org/wiki/Proof_of_work
- aquark 15y agoI'm not familiar with the details of bitcoin, but in that case aren't (some of) the inputs to the function hidden not the function itself. Proof of work techniques are relying on forcing the other party to run a known function in order to prevent various attacks. If the other party can't verify the result they would be no use.