Is “double hashing” a password less secure than just hashing it once?

Question

Is hashing a password twice before storage any more or less secure than just hashing it once?

What I\'m talking about is doing this:

$hashed_password         


        

Answer 1

Personally I wouldn't bother with multiple hashses, but I'd make sure to also hash the UserName (or another User ID field) as well as the password so two users with the same password won't end up with the same hash. Also I'd probably throw some other constant string into the input string too for good measure.

$hashed_password = md5( "xxx" + "|" + user_name + "|" + plaintext_password);