Salt

Salt

In cryptography, a salt is random data thatis used as an additional input to a one-way function that “hashes” a passwordor passphrase. Salts are closely related to the concept of nonce. The primary function of salts is to defend against dictionary attacks versus a list ofpassword hashes and against pre-computed rainbow table attacks.

A new salt is randomly generated for eachpassword. In a typical setting, the salt and the password are concatenated andprocessed with a cryptographic hash function, and the resulting output (but notthe original password) is stored with the salt in a database. Hashing allowsfor later authentication while protecting the plaintext password in the eventthat the authentication data store is compromised.