Login
π¨βπΌ Stellar! Now we can really be sure the user is who they say they are when
they log in. Next, let's add some utilities that will make it much easier to
access the user's information throughout our UI from anywhere in the app.
Timing Attacks
π¦ I want to take a moment to talk about timing attacks. We're currently
vulnerable to these though it doesn't matter to us. A timing attack is
essentially a way to figure out a secret by measuring how long it takes to
perform an operation. In our case, we're vulnerable because we're using
bcrypt.compare to compare the user's password to the hash in the database.
But before we do that, we're checking to see if the user exists. If the user
doesn't exist, we return early.So an adversary could determine if a user exists by measuring how long it takes
to get a response from the server. If the user doesn't exist, the response will
be faster than if the user does exist.
In our application, the users are public knowledge so it doesn't matter if an
adversary can figure out if a user exists or not. Additionally, we require the
username to be unique so an adversary could simply sign up for an account to
figure out if a user exists or not.
But, imagine a scenario where an adversary is trying to determine if a user with
a specific email has an account at a certain bank. That would probably be a bad
thing, so it would be a good idea for that bank to hide the fact that a user
exists or not. They could do this by always returning a response, even if the
user doesn't exist and ensuring that response takes a random amount of time
regardless of whether the user exists or not.
Kellie's work
π§ββοΈ I'm going to make a few changes for you to help you focus on your task,
specifically, I'm going to:
- add a (non-functional) logout button to the user's page if they're looking at their own profile.
- Only display the note delete and edit buttons if the user is the owner of the note.
- Only display an "add note" link if the user's looking at their own notes.
None of these will be wired up (that's your job), but they'll help you see what
you're working towards. And it's important to note that just because we don't
display the UI for something, it doesn't mean the user can't do that with
sophisticated tools so we'll definitely want to add some logic on the backend
too. We'll get to that later though.
As always, if you want to, you
can review my work.
