3 ms·

I would have optimized your last paragraph - "Why don't you hash the given password, and then check for the user, and then their password hash?" and then realiz

I would have optimized your last paragraph - "Why don't you hash the given password, and then check for the user, and then their password hash?" and then realized I was in error. The time taken to hash or not is definitely noticeable, but unless you take steps to avoid it, even the string comparison of hashes can leak timing information. Edit: As noted in an earlier comment, below. Whoops.

carbocation 15y ago
Since bcrypt uses a random salt, the approach that I think you are suggesting (hash the input pass, check the user, and then strcmp the hashed pass in the database with the hashed pass from user input) would not work. Try bcrypting the same string repeatedly and you'll see that the same string produces different output each time.