A set of requirements regarding password creation, storage, and usage. These requirements often constrain several characteristics of passwords. So, a password policy is a set of rules designed to enhance computer security by encouraging users to employ strong passwords and use them properly.

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470
votes
14answers
80k views

What technical reasons are there to have low maximum password lengths?

I have always wondered why so many websites have very firm restrictions on password length (exactly 8 characters, up to 8 characters, etc). These tend to be banks or other sites where I actually care ...
46
votes
9answers
18k views

How long should the password be?

The minimum password length recommended is about 8 characters, so is there any standard/recommended maximum length of the password?
41
votes
7answers
34k views

Is saving passwords in Chrome as safe as using LastPass if you leave it signed in?

Justin Schuh defended Google's reasoning in the wake of this post detailing the "discovery" (sic) that passwords saved in the Chrome password manager can be viewed in plaintext. Let me just directly ...
29
votes
4answers
4k 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 ...
59
votes
8answers
11k views

Is password reuse a problem if the password is very strong?

I always read that using the same password on multiple sites is a risk. I'm wondering what is the real reason for this? In my case, I use the same password on multiple sites everywhere. My password ...
4
votes
4answers
1k views

Best practice for forgot password form, ok to leak that a given e-mail is invalid

On our forgot password reset form, is it ok to leak that a given e-mail address entered is invalid? Or should we always just return success and check your e-mail, even if the e-mail is not valid. I ...
54
votes
9answers
22k views

Why Disallow Special Characters In a Password?

The culprit in this case is a particular (and particularly large) bank that does not allow special characters (of any sort) in their passwords: Just [a-Z 1-9]. Is their any valid reason for doing ...
30
votes
5answers
5k views

Is it common practice to log rejected passwords?

While selecting unique passwords for each purpose is a great idea, in practice this rarely happens. Therefore many select passwords from a personal pool of passwords that are easily remembered. When ...
9
votes
2answers
743 views

Banning specific passwords?

There have been a couple of questions about enforcing good passwords, so I thought I'd add my own: In addition to enforcing a minimum Shannon entropy, would it generally be a good practice to ...
23
votes
3answers
3k views

Should I have a maximum password length?

I'm creating a webapp, and part of my authentication method is password length. Should I put one in place? (say, 50 characters?) Or should I just put a minimum length (Currently at 6). Are there ...
8
votes
4answers
850 views

Doesn't imposing a minimum password length make the password weaker by reducing the number of possible combinations?

I thought the strength of a password depended on the total number of possible combinations. Therefore, allowing longer passwords should be safer because you then have more possibilities. But why do ...
19
votes
4answers
4k views

The registration confirmation email contains my password: do they keep it in plaintext?

I was kind of shocked when I just received my confirmation mail from the shop where I just registered myself: they sent my username (which is my email address) and the password I typed in. The ...
9
votes
3answers
2k views

How often should passwords change?

I'm asking two very related questions As an admin what policies should be enforced regarding the frequency of password changing? I have an idea that users should be forced to change their ...
14
votes
7answers
1k views

Aren't password managers still incredibly risky?

I understand the utility in having one application remember a bunch of long, randomized passwords, but all you'd need is one well-placed phishing scam or a keylogger and they get all the keys to the ...
26
votes
12answers
8k views

How secure are passwords made of whole english sentences

I often read as an advice to build strong passwords, just to think about a sentence and then take the initial letters. For example take a nonsense sentence like "I watch Grey's Anatomy at 9.40" gives ...
26
votes
7answers
4k views

Does username length/complexity/uniqueness positively impact security?

Is having a longer/more complex username considered more secure than using a shorter/basic one? Would the uniqueness of a username positively impact security? This is assuming that adversaries aren'...
26
votes
6answers
5k views

Why do some sites prevent users from reusing their old passwords?

I have always wondered why it is that bad to reuse old passwords; it should not be the end of the world if we happen to use an old password that we previously used. After all, I believe most of the ...
8
votes
3answers
804 views

An alternative to traditional passwords: is there some merit to this idea?

If you've got a website aimed at people that are not neccessarily technically proficient, letting new users choose their own password isn't very secure because of the simple fact that a lot of people ...
4
votes
3answers
629 views

Password strength metrics

In the question Source code as password I suggested using a combination of entropy and as @Lawtonfogle put it 'meatspace difficulty'. As suggested in the xkcd comic correct staple horse battery is a ...
4
votes
7answers
4k views

Is it possible to detect password length from hash? Does doubling your password add more security?

Assuming a service doesn't store a plain text password, am I right in saying that the answer to this question depends on the service? On a bad service, the hash length is related to the password ...
139
votes
16answers
18k views

Is the BBC’s advice on choosing a password sensible?

In this article on the BBC’s website they offer advice on how to develop a password. The steps are as follows. Step 1: Choose an artist (a recording artist I presume) Lets choose as an example ...
12
votes
5answers
2k views

Passwords - any statistics on user behavior?

I'm looking for analyses of how users choose and use passwords. I'm sure there are many resources out there that analyze user passwords. For instance, I've seen many people analyze dumps of password ...
12
votes
3answers
593 views

Is it inconsistent to tell users to “not click on password links in email”, and requiring clicks on “forgot password” links?

On one hand, IT Security shops have been telling users to not click on links in email because they can do damage to your computer, or phish your personal information. Many of those issues are ...
22
votes
2answers
5k views

Why are passwords limited to 16 characters?

What is the reason that most websites limit to 16 characters? I would have thought the longer the password the more difficult it makes it for someone to crack it? Is it something to do with hash ...
5
votes
5answers
6k views

Password reset links: random value or authenticated message?

Which is better? Create tamper-proof encrypted password reset token which contains the user id and the expiration time within the encrypted token. Generate a random token and store it in the ...
11
votes
4answers
1k views

Does it indicate a bad password system to disallow certain characters in passwords?

When creating an account to the game League of Legends, the user's password must comply to a few rules. The one I'm concerned about is the "Must not contain slashes or spaces" one. The others are ...
8
votes
8answers
2k 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 ...
3
votes
3answers
166 views

Account-lock security policy (username/password)

I am currently working on an application with regard to applying a security policy to the application. We are locking the account after X failed login attempts in Y minute. The account will be locked ...
4
votes
1answer
333 views

How does the mobile security technology APNS and 3LM work?

APNS is an iPhone technology that assists with mobile push. 3LM is a BIOS-level security technology embedded in certain Android phones. I recently got off the phone with Boxtone and they said they ...
4
votes
5answers
330 views

How many combinations does a specific password policy allow?

Recently I was arguing about password policies. Assume you have a policy which requires 10 characters and additionally at least one letter, one number and one special character. My companion was ...
2
votes
2answers
163 views

What is the evaluation criteria that a site uses for a password as strong , moderate or less secure

I have been in kind of jinx as to how a website decides on which password is highly vulnerable , strong etc . Lately my yahoo account was told to change password which I am using for long time as the ...
1
vote
2answers
148 views

Is it a good idea to combine words from different languages to increase a password's strength? [duplicate]

I was thinking of a way to generate a password that is easy to remember, but hard to crack, like the famous "correct horse battery staple" suggested by XKCD, also discussed here, and I've realized I'...
1
vote
3answers
307 views

Should I trust my bank after this [closed]

I have just discovered that I can login to my bank with passwords that is not mine. Example: My password is "1234" but I am authorized with all possible post characters. For example "12345" or "...
-2
votes
3answers
299 views

Password security : complexity and length [duplicate]

Possible Duplicate: XKCD #936: Short complex password, or long dictionary passphrase? I've read that there is many solutions available to crack passwords. Reading these tips, I can understand ...
-4
votes
1answer
2k views

Good Password Length [duplicate]

If you are looking to be careful and your passwords include all the types of characters, what is the ideal password length?
193
votes
7answers
40k views

Why would you not permit Q or Z in passwords?

Jetblue's password requirements specify that, among other stringent requirements: Cannot contain a Q or Z I can't fathom a logical reason for this, unless it were say, extremely common for the ...
65
votes
12answers
10k views

Do we really need a long and complicated password for websites?

Most of websites that handle important information (Gmail, for instance) have some kind of brute force protection. Sometimes if you try more than X times it will lock the account or at least give you ...
25
votes
10answers
6k views

Best password strength checker

In XKCD #936: Short complex password, or long dictionary passphrase? Jeff claimed that password cracking with "dictionary words separated by spaces", or "a complete sentence with punctuation", or "...
4
votes
3answers
9k views

What do I need to do to secure log-in and registration for my website?

What security features do I need to have in-place to ensure that my website log-in and registration forms are secure?
22
votes
5answers
4k views

Does too long a salt reduce the security of a stored password hash?

Suppose we have passwords that are statistically 7-8 characters long. Is appending a 200 character long salt less secure than a 5 character salt, because of the similar hash function inputs? I was ...
20
votes
4answers
5k views

Would allowing shorter passwords sometimes be more secure?

Does the act of requiring certain criteria for passwords make them easier to brute-force? It's always seemed to me that when websites limit the use of "insecure" passwords, it might make it easier ...
28
votes
6answers
15k views

Sharing wifi at a business - Bad Policy?

Is it safe for a small business to let customers use their wifi while waiting? My friend is starting up a small dentistry practice (1 dentist), and I'm setting up his computers/wifi as a favor. He'...
37
votes
9answers
4k views

Why do password strength requirements exist?

Password strength is now everything, and they force you to come up with passwords with digits, special characters, upper-case letters and whatnot. Apart from being a usability nightmare (even I as a ...
34
votes
8answers
2k views

Who is responsible for the strength of user's passwords?

Who is responsible for a user's password's strength? Is it us (developers, architects, etc.) or the user? As a web developer, I've frequently wondered whether I should enforce the minimal password ...
15
votes
8answers
4k views

What chars should I not allow in passwords?

I am planning to develop a website that require that the users register a username and a password. When I let the user choose a password, what chars should I allow the users to have in the password? ...
32
votes
4answers
3k views

What is the point in having arbitrary username requirements?

I've looked around on Security.SE, but couldn't find much related to the following problem: I recently signed up for Chase Quick Pay as my method of being paid by a part-time job. I've heard of ...
10
votes
3answers
1k views

Logging “password with counter” use

When prompted to update their passwords after they've become stale (whether that's after 30, 60, 90 days — whatever is implemented by policy), many users simply increment the number that they may have ...
12
votes
4answers
2k views

Are single case alphanumeric passwords the most user friendly?

We are often advised, or required, to compose passwords containing all of the following: numerals, lower case letters, upper case letters and some special characters. In my view this is not the best ...
9
votes
11answers
4k views

How to easily remember lots of different passwords?

I know that you shouldn’t use the same password on every site. But, when you log into several dozen sites, keeping track of all the passwords can be pretty hard. What system do you recommend that won’...
8
votes
4answers
2k views

password complexity policy for non “English” passwords

In an internationalized application, what is the best practice for a policy on complexity of passwords? I am not having luck searching for the answer. Wikipedia lists these items for password policy:...