A non-crypto hash is run enough to confuse "simple" statistical tests. A crypto-hash is run enough times to confuse "difficult" statistical tests from a dedica

A non-crypto hash is run enough to confuse "simple" statistical tests. A crypto-hash is run enough times to confuse "difficult" statistical tests from a dedicated adversary. For example, the JOAAT hash is a simple add / shift / XOR hash run 1x round per byte. A singular round is all you need to confuse the "simple" statistical tests such as birthday attacks, dice rolls, etc. etc. SHA-256 is also a simple add / shift / XOR hash, albeit using 256-bits at a time instead of 8-bits at a time. It is a 64-round hash function. That is: it is round(round(round(round(data)))) 64-times deep. -------- If you wanted to turn JOAAT non-crypto hash into a crypto-hash, a good first step would be to run JOAAT(JOAAT(JOAAT...() maybe 64x or 128x over the data. Obviously, you'd need to run cryptoanalysis over the end result, and also test for non-linearity and other such properties. But "large number of rounds" is probably the most obvious difference between non-crypto and crypto hashes. --------- In the 90s, functions like AES were designed with "maximum confusion / diffusion per round". In just 10 rounds, the bits are mixed up enough that it defeats linear and differential cryptography. I don't know which cipher "changed the meta", but maybe it was the XTEA cipher? Since XTEA was so simple, they knew it would need many-many rounds to defeat linear and differential crypto. So they just did 64-rounds and called it the end of it. ---------- So you can see, a "crypto" hash is effectively a regular old hash done an absurd number of times to defeat the most incredible statistical-tests known to man... done under the assumption that the "opponent" is performing the most difficult statistical tests.