Linked Questions

6
votes
2answers
3k views

How facebook knows my new password is too similar to my old password? [duplicate]

I am still very new to Information Security field and as far as I know, websites use hashing algorithm on user's passwords before storing it and they don't know the plain-text password of a user. ...
837
votes
13answers
241k views

How to securely hash passwords?

If I hash passwords before storing them in my database, is that sufficient to prevent them being recovered by anyone? I should point out that this relates only to retrieval directly from the database,...
516
votes
3answers
86k views

Why can I log in to my Facebook account with a misspelled email/password?

I've been playing around with different login forms online lately to see how they work. One of them was the Facebook login form. When I logged out of my account my email and password were ...
52
votes
6answers
10k views

How can a system enforce a minimum number of changed characters in passwords, without storing or processing old passwords in cleartext?

In some environments, it is required that users change a certain number of characters every time they create a new password. This is of course to prevent passwords from being easily-guessable, ...
32
votes
4answers
7k views

Is it safe to store a password hash history for preventing user to keep same password repeatedly in some cases?

I am developing an application in PHP and it uses bcrypt encryption to store passwords. I want to keep the history of hashes whenever the user changes the password. By doing this I want to stop the ...
35
votes
4answers
5k views

Does Facebook storing old passwords compromise security? [duplicate]

Facebook stores old password hashes (along with the old salt), such that if you try to log in with a previous password, Facebook tells you that you updated the password (and when). Nice user ...
47
votes
1answer
8k views

Facebook password lowercase and uppercase [duplicate]

Recently I logged into my Facebook account and then noticed that my caps lock was on. So I tried to log in again with and without capslock on. I got in both times. Then I tried to log in with the ...
11
votes
7answers
4k views

How to securely counter users from adding a single digit to their old password upon creating a new one? [duplicate]

Let's say that in the password policy the password history is defined to remember the last 10 passwords. I understand password history exists so that if a password is recovered from a compromised ...
31
votes
2answers
4k views

Why does Facebook bother comparing old and new passwords?

An answer to this question says Facebook generates a bunch of password guesses to see if they hash the same as a previous version of the password. Why bother? If a service forces every password to ...
20
votes
2answers
5k views

Company can tell if new and old passwords are too similar. Is there a security problem? [duplicate]

I've spoken to an employee of a big international company in germany. He said, employees are warned if their new password is too similar to the old password. (e.g. if they change the password from ...
24
votes
3answers
4k views

Do servers store my previous passwords?

When I change my password on some web servers like email, cloud, and social networks and try to use my previous password, the server denies it with message "Don't use your previous passwords". Does ...
10
votes
8answers
4k views

Sequential password updates

Let's say I have a reasonable KDF, and that I make users change their passwords periodically and keep some old password hashes to prevent password reuse. What's to stop the user from changing the ...
10
votes
3answers
4k views

How can I store a password history to prevent reuse?

I have an application with a user database. The database stores the password using a bcrypt hash with a randomized salt. How can I implement a password history set (to prevent password reuse) in a ...
12
votes
4answers
1k views

Password security

I was requested at the login page of a website to first change my password. After typing in a new password, the web page told me the new password did not differ enough from the previous one. Does this ...
4
votes
4answers
3k views

How to tell if a site is securely storing passwords? [closed]

A site I frequent has a policy to make you change your password every 90 days. That's a cool policy, but I stumbled upon an old xkcd and facepalmed myself, because lots of doxing happens on this site. ...

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