Salts aren't meant to be secret; they are generally stored next to the hashes (and used in a known, standard way). The purpose of the salt is to raise the cost

Salts aren't meant to be secret; they are generally stored next to the hashes (and used in a known, standard way). The purpose of the salt is to raise the cost of brute-force attacks, by forcing attackers to brute-force each password separately. https://en.wikipedia.org/wiki/Rainbow_table https://en.wikipedia.org/wiki/Rainbow_table