Question

I have a string which is a SHA256 hash, and I want to pass it to a Python script which will convert it to a SHA256 object. If I do this:

my_hashed_string = // my hashed string here
m = hashlib.SHA256()
m.update( my_hashed_string  )

it will just hash my hash. I don’t want to hash twice…it’s already been hashed. I just want python to parse my original hashed string as a hash object. How do I do this?

Answer 1

Unfortunately the hash alone isn’t enough info to reconstruct the hash object. The hash algorithm itself is temporal, depending on both internal structures and further input in order to generate hashes for subsequent input; the hash itself is only a small piece of the cross section of the algorithm’s data, and cannot alone be used to generate hashes of additional data.