how to set the seed for mimc hash about gnark

[ThomasPiellard]

Hi, as it is now the seed should be a random string, without particular principles about it. The constants used in the mimc encrypt function are derived from computing successive SHA3 of the seed.

This part is a bit dirty, and we will change it at some point so hash.MIMC_BN256.New takes a io.Reader as source of randomness (like what you would find in golang's crypto/ package). We implemented the New function for the hashes like this because when using mimc in a snark circuit, we need to instantiate the mimc gadget with the same seed as the one used in the real go implementation.

We did a clean pass on eddsa to fix this kind of problem, and we will do the same with the hash functions.

[mdj33]

so if we take a random data from io.Reader as the seed, it should be quite safe from crack the hash point of view, is it?