A rainbow table is ineffective against one-way hashes that include salts. For example, consider a password hash that is generated using the following function (where "." is the concatenation operator): saltedhash(password) = hash(password.salt) or saltedhash(password) = hash(hash(password).salt).

The salt value is not secret and may be generated at random and stored with the password hash.

Which software is it you design? I'd like to know so I can avoid it at all costs in the future.