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.

learn more… | top users | synonyms

343
votes
12answers
56k 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 ...
176
votes
7answers
38k 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 ...
77
votes
8answers
10k views

Why not allow spaces in a password?

"Your password can't contain spaces." is a message I see from some websites, including 1 . Why? (This question is very similar to Why Not Allow Special Characters In a Password? , but the answers ...
56
votes
13answers
8k 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 ...
45
votes
9answers
13k 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 ...
44
votes
8answers
6k views

Do bad passwords produce bad salted hashes?

When you have a password stored in a database that has been strongly hashed and salted does it really matter if the underlying user password is weak? If you setup features like limiting login ...
37
votes
9answers
10k 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?
36
votes
9answers
3k 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 ...
31
votes
4answers
3k views

Is it safe to show users why their password is not allowed?

/////////////////////////////// Updated Post Below //////////////////////////// This question has received a lot of hits, more than I ever thought it would have on such a basic topic. So, I ...
31
votes
5answers
2k views

Are there any guidelines for passwords that need to be read out loud?

I recently saw the movie Olympus Has Fallen. Like in many action movies, at the end a missile is launched, and the hero (Mike Banning, played by Gerard Butler) has 60 seconds to recall the launch in ...
30
votes
3answers
2k views

Is there a security reason for a site to limit the number of times a user can change their password?

Is there a security reason to disallow a user to change their password as frequently as they want? I have found this security policy in a site and I am not sure why it is enforcing it. One reason I ...
29
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 ...
29
votes
4answers
3k views

New payment option on Paypal “Enter your online banking ID + password”: Any mechanism that could make this safe?

Paypal has a new payment option called "Bank Account" which says: Enter your online banking ID + password QUESTION: To me it sounds unsafe (ie: sends my password to a third-party organization ...
26
votes
12answers
5k 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
4answers
3k 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 ...
25
votes
6answers
11k 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. ...
24
votes
5answers
3k 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 ...
23
votes
10answers
6k views

Intel How Strong is Your Password page, good advice?

I came across this Intel How Strong is Your Password? page which estimates how strong your password is. It has some advice on choosing better passwords including that you should use multiple ...
23
votes
5answers
2k views

Do spaces in a passphrase really add any more security/entropy?

I often see passphrase suggestions written as a sentence, with spaces. In that format are they more susceptible to a dictionary attack because each word is on it's own as opposed to a large unbroken ...
22
votes
10answers
4k 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 ...
21
votes
6answers
3k 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 ...
20
votes
5answers
3k 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
5answers
16k 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 ...
19
votes
4answers
3k 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 ...
18
votes
1answer
916 views

Does a maximum length of password mean non-hashed storage?

When a system requires a password between say 6 and 20 characters in length, does it mean the password is stored without using a hashing function, and that the mysql-field (or similar) is 20 ...
18
votes
3answers
3k 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 ...
17
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 ...
16
votes
3answers
2k views

Why do some bank websites use passwords that are not case sensitive?

It was recently brought to my attention that a certain big bank website allows users to log in with passwords that are not case sensitive. After confirming this, I checked other websites I bank with ...
15
votes
4answers
1k views

My credit union is reducing its maximum password length to 10 characters

I just received an email from my credit union saying they are redesigning their online banking service and that I will need to change my password by October 22 to conform to the new limit of 10 ...
12
votes
7answers
2k views

Why don't we reward users who choose strong passwords? [on hold]

Suppose there is a web property that has some sort of reward system or commodity that its users desire. It could be reputation on Stack Exchange-like sites, rank badges on message boards, or add-on ...
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 ...
12
votes
3answers
472 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 ...
11
votes
2answers
714 views

How can I find out the password hashing schemes used by the specific Unix accounts I log in to?

Every day I ssh in to 3 or 4 independent Unix accounts. I have been regarding them as more or less "equivalently secure" on the grounds that I'm using ssh, but after learning of how much variety ...
11
votes
2answers
1k views

Requiring regular password change but storing previous paswords?

My bank requires me to change my password regularly but then they can detect if my password was used before. They probably store the old password (possibly hashed) in order to detect it. I think this ...
11
votes
4answers
878 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 ...
11
votes
2answers
1k views

Password auditing

Most password policies require the password to be at least 8 characters long and contain symbols from at least 3 classes (lower case letters, upper case letters, numbers, other). Problem is, that a ...
11
votes
7answers
919 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 ...
11
votes
4answers
528 views

What is the best way to hand out passwords to a widely spread diverse employee base?

I have a problem I need to solve - specifically, how to hand out passwords to people in a variety of locations, and with a wide variety of access. I've thought of some options, but there are ...
10
votes
3answers
309 views

Is there any conceivable reason to prevent a password change in an authentication system?

I connect to the VPN of another company with a company-specific username and password (they aren't giving everyone the same password to every company to access it or anything ridiculous like that.) ...
10
votes
3answers
611 views

How can I promote good password practices in an organization that doesn't currently care about that?

I work with an organization that uses some very poor practices such as using default user accounts, default passwords (or passwords the same as user accounts), sharing password information between ...
9
votes
8answers
1k 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 ...
9
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 ...
9
votes
4answers
8k views

Regulations that specify password length?

I have read: PCI DSS 1.2 SOX 404 AR 25-2 ISO 27001 But only PCI DSS specifies a minimum password length. Are there any other regulations that dictate password lengths for any industry? NIST ...
9
votes
3answers
938 views

Requirement to send username and password in distinct email messages

I have an application that sends username and a password by email (random temporary password, mandatory change on first login). A big customer has this policy of "never send username and password in ...
8
votes
4answers
651 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 ...
8
votes
7answers
817 views

How can I prevent users from using bad passwords in my web application?

There is a long discussion on whether it's the responsibility of the user or the system administrator to deal with the strength of the password. Obviously, the password is a very private thing, but ...
8
votes
4answers
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 ...
8
votes
11answers
2k 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 ...
8
votes
4answers
2k views

Is forcing users to change passwords useful?

In many places, there's a policy that force the user changing it's password once a few months. The logic here is, that even if the password have leaked somehow, it'll be abused only for a relatively ...