how to reverse Python uuid5() to its value?

Question

can it be reversed? if I use

>>> RESOURCE_ID_NAMESPACE = uuid.UUID('0a7a15ff-aa13-4ac2-897c-9bdf30ce175b')
>>> value = 'test'
>>> uuid.uuid5(RESOURCE_ID_NAMESPACE, value)
UUID('7fd19145-920f-5b9c-be0a-2146b0c39949')

if I know the uuid5 value, can I get the value 'test'?

thanks a lot.

Answer 1

UUID version 5 is based on the SHA-1 hash of the input. The whole point of cryptographic hashing algorithms is that they're nearly impossible to reverse in the general case.

If you know the input was a dictionary word, sure, you could just generate a uuid5 value for every word in the dictionary, same goes for when you know it's a short string of letters, but in the general case, no, you can't reverse a UUID5 value any more than you can a cryptographic hash. And no, the weaknesses in SHA-1 are unlikely to be helpful here; they're useful largely in generating collisions, but not recovering the original value.

Answer 2

No, you cannot. The uuid is created by hashing the namespace and value you pass into the constructor. But there are an infinite number of other possible strings (although they're probably hard to find) that hash to the same value. So there's no way to determine what the original string was that constructed the uuid.