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by thequux 7 days ago
I can't judge the veracity of the history of hash functions, but the moment it starts talking about cryptography it goes completely off the rails: it seems to indicate that finite field exponentiation o'r high degree polynomials are used in cryptographic hash functions; they are emphatically not. It presents password hashing as just applying a suggest function to the password; in practice a KDF is used, which is a completely different design space (for a start, KDFs have a tweak parameter, usually called a salt in this context). Finally, there's a haven't reference to quantum computers breaking hash functions and needing post-quantum algorithms as a result. This does brush with reality in that Grover's algorithm does theoretically eat half the first preimage resistance security level of your hash function, but even SHA256 will require 2^128 iterations on a quantum computer, which will likely never be feasible. Worse, it doesn't help at all in attacks against second perimeter resistance or collision resistance.

Considering that everything I have personal knowledge of here is obviously bunk, best ignore the rest of it too

2 comments

Author here. In the article I explicitly mention that the second part (about high degree polynomial and descrete exponentation) is based on Diffie-Hellman's 1976 paper and presents their one-way function constructions, not MD5 or SHA family (my goal is to cover the history of hashing from the beginning, so I haven't done a research on modern systems yet).

As for the quantum computing stuff, I should have stated more clearly that I'm referring only to quantum computer allowing to calculate descrete logarithms rather fast, and provided a source such as https://math.mit.edu/~shor/elecpubs.html containing a link to the paper Algorithms for quantum computation: Discrete logarithms and factoring by Peter Shor. (I'm planning on covering post-quantum cryptography after I'm done with modern algorithms)

O’r?