Salting Hashes - why is the salt treated by the literature as being known to Eve?

Question

The title says everything. I don\'t understand: why you shouldn\'t keep your salt a secret like the password. Or did I misunderstand something?

Answer 1

The purpose of salt is making an attack on several crypted passwords at the same time harder. It doesn't make an attack on a single crypted password harder.

With a salt, an attacker has to test each candidate plaintext password once for every different salt.