Any salt at all will obviously help when salting and hashing a user's password. Are there any best practices for how long the salt should be? I'll be storing the salt in my user table, so I would like the best tradeoff between storage size and security. Is a random 10 character salt enough? Or do I need something longer?
5 Answers
Currently accepted standards for hashing passwords create a new 16 character long salt for every password and store the salt with the password hash.
Of course proper cryptographic care to create really random salt should be taken.
The SHA2-crypt and bcrypt methods—used in Linux, BSD Unixes, and Solaris—have salts of 128 bits. These larger salt values make precomputation attacks for almost any length of password infeasible against these systems for the foreseeable future.
128-bit (16-byte) salt will be enough. You can represent it as a sequence of 128 / 4 = 32 hexadecimal digits.
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