Constant MIN_SALT_LEN 

pub const MIN_SALT_LEN: usize = 16;

Minimum acceptable salt length (in characters, after trimming) for the sha2_salted pseudonym to be considered safe.

TUNABLE: 16 is the hard floor below which a salt over enumerable ids is brute-forceable. A high-entropy random salt of >= 32 characters is strongly recommended in production. Raise this constant to tighten the policy.