On Fri, Sep 8, 2017 at 9:53 AM, Owen Jacobson <o...@grimoire.ca> wrote:
> $ echo 'It is possible to win by destroying Stamps in the possession of > others' | shasum -a 256 > 204aa33ed7c42e58d6f391b3878dc89738c8a1bb95b39b3ebcda2609c1fabe3c - On Sep 7, 2017, at 7:55 PM, VJ Rada <vijar...@gmail.com> wrote: > Can you explain to a technological neophate how to decrypt that? It’s not really encryption, so you can’t decrypt it. The idea is that the ‘sha256’ algorithm takes a document as input, and produces an opaque value as output. The output value has the interesting property that if two outputs are equal, it is nearly certain[0] that the inputs are equal. Yesterday, I said I knew something whose SHA256 hash is 204aa33ed7c42e58d6f391b3878dc89738c8a1bb95b39b3ebcda2609c1fabe3c. Today, I provided the input document, and a command you can use to verify that it has the same hash. This means it’s almost certainly the same document I already knew, yesterday - you can verify it yourself, without having to have access to either a time machine or psychic powers. Gaelan did a similar thing, though he used a larger hash. -o [0] Specifically, given to arbitrary documents as inputs, there is a 1 in 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936 chance that they have the same SHA256 hash. For all intents and purposes, unless there’s an as-yet-undiscovered weakness in the algorithm, a SHA256 hash uniquely identifies a document.
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