81eb1cf42dc766553d51bc73d70adebe8607031b

Question

who knows what kind of hash is this ??

Answer 1

https://en.m.wikipedia.org/wiki/List_of_hash_functions
There are four results with 160 bits (20 bytes).

Answer 2

Rijindael-256 algorithm!
I dehashed here: https://codebeautify.org/encrypt-decrypt

Answer 3

thanks for the answer