Specific to the security of passwords: hashing, entropy, cracking, resets, lockouts, etc.

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Why are GPUs so good at cracking passwords?

What is it about GPUs that lets them crack passwords so quickly? It seems like the driving force behind adopting good key-derivation functions for passwords (bcrpyt, PBKDF2, scrypt) instead of ...
25
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6answers
3k 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 ...
25
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5answers
3k views

Should passwords be revealed in error message?

I am having pet-peeve with PHP's PDO class. As you can see on the Warning note: it reveals database password by default if an exception was not caught (when display errors is on which is a probable ...
25
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1answer
2k views

Facebook password lowercase and uppercase

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 ...
25
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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 ...
24
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6answers
2k views

Online password managers

Can online password managers be used for storing and managing passwords? I mean from the security point of view. I understand that those systems can be different and some deserves more trust than the ...
24
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10answers
7k 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 ...
24
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4answers
3k views

What to transfer? Password or its hash?

Let's say in my database I store passwords hashed with salt with a fairly expensive hash (scrypt, 1000 rounds of SHA2, whatever). Upon login, what should I transfer over the network and why? Password ...
24
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6answers
5k views

Source code as password

Passwords with a mixture of letters, numbers, and special characters are sometimes hard to remember. Is it secure to instead use a small amount of memorable source code as a 'passphrase'? As an ...
24
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3answers
5k views

Security of LastPass + YubiKey

I'm looking at password manager solutions and came across LastPass. I see they also support two-factor authentication using YubiKeys. How secure is this combination for password management? What are ...
24
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10answers
5k views

Password Management within an Organisation

Within an organisation there are many passwords such as those for root accounts on servers, hosting accounts, router logins and other such things, that need to be kept track of. I know in some ...
23
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11answers
5k views

One liner to create passwords in linux?

How do you create a readable password using bash with one line? What if i'm looking for 128 bits of entropy? EDIT By readable I mean the 94 printable ascii characters (without space). It can use ...
23
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4answers
5k views

What is the purpose of the “Password minimum age” setting?

What additional security can a "password minimum age" provide? For example: the user can change their password only after 24 hours have elapsed since the last password change.
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4answers
5k views

Why did Richard Stallman recommend not to use passwords for wireless networks? [closed]

In a short interview, Richard Stallman recommends not to put passwords on your wireless network. In the OS Revolution documentary he also mentions how he's disliked passwords ever since his job at MIT ...
23
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5answers
7k views

Password strength and banks 4 pin code?

Why is it that some security advisers recommend using an 8 character password with upper, lower, digits, and symbols while banks only use a 4 digit number pin for debit and 3 digit pin for credit ...
23
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2answers
3k views

Passwords in plaintext?

I'm doing some research on the App of my telephone operator. I started Burp Suite on my Mac in proxy mode, I opened up the App on my iPhone and started to sniff some traffic. I pressed the "login" ...
23
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5answers
3k views

Recommended policy on password complexity

Is there any research on how how a password complexity policy can increase or decrease the quality of passwords? If you don't have any requirements on the password then probably 90% of users will use ...
23
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5answers
2k views

Is it possible to increase the cost of BCrypt or PBKDF2 when its already calculated and without the original password?

I just wanted to know if you can increase the cost (iterations) of those two algorithms off-line. I want to increase the cost every year of my users passwords. One solution is to recalculate them ...
23
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5answers
3k views

How can I choose a strong password that is easy use on a smartphone?

Typing on a smartphone is tedious. Special characters are the hardest; lowercase letters are generally the easiest. But even a long all-letter passphrase like "correct horse battery staple" is ...
22
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13answers
4k views

Why do we even use passwords / passphrases next to biometrics?

In the last couple of days there were a lot of talking about passwords and passphrases, not only here, but on several blogs and forums I follow (especially after XKCD #936 saw the light of this ...
22
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7answers
8k views

Why don't people hash and salt usernames before storing them

Everyone knows that if they have a system that requires a password to log in, they should be storing a hashed & salted copy of the required password, rather than the password in plaintext. What I ...
22
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3answers
2k views

Does overlaying the mouse on a virtual numeric keyboard really protect against keyloggers?

I just saw for the first time a new way to enter a password, at the Banque Postale (French Bank). You are given a virtual numeric keyboard and to type you can just leave the mouse cursor over a number ...
22
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3answers
15k views

Is bcrypt better than scrypt [duplicate]

Possible Duplicate: Do any security experts recommend bcrypt for password storage? I'm no security expert and do not pretend to be that's why I'm asking here. I write many PHP based ...
22
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1answer
2k 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 ...
22
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4answers
4k views

How would you store a 4 digit pin code securely in the database?

I'm familiar with password hashing, using salts, bcrypt etc. But it doesn't seem like this would work to store a 4 digit pin code since the attacker could try all 10,000 combinations quite quickly. ...
22
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4answers
11k views

Confused about (password) entropy

There seem to be many different 'kinds' of entropy. I've come across two different concepts: A) The XKCD example of 'correcthorsebatterystaple". It has 44 bits of entropy because four words randomly ...
22
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4answers
6k views

How secure is NOPASSWD in passwordless sudo mode?

On all our boxes we have ssh access via keys. All keys are password protected. At this moment the sudo mode is not passwordless. Because the number of VMs are growing in our setup, we investigate the ...
22
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1answer
1k views

How does Firefox encrypt passwords without selecting Master Password?

I know that the file logins.json contains all my encrypted passwords in Firefox browser. How does Firefox encrypt these passwords if I don't use the 'Master Password' option? Does this mean key3.db ...
22
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3answers
1k views

How can we accurately measure a password entropy range?

I've given myself the task of writing code that determines the strength of a password, and really want to break out of a lot of already established ways we do that, as they're often lacking, not ...
22
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4answers
8k views

How secure is Windows 8's Picture Password login?

The final Windows 8 build has been released to manufacturing. One of the new features of Windows 8 is "Picture Password", where the end user logs on to Windows by clicking a specific pattern on the ...
21
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8answers
21k views

Why do people still use/recommend MD5 if it is cracked since 1996?

It's still commonly recommended way of hashing passwords, even if it's insecurity had been proven in 1996 Therefore we suggest that in the future MD5 should no longer be implemented in ...
21
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4answers
9k views

Should I change all my passwords due to heartbleed [duplicate]

Should I change all of my online passwords due to the heartbleed bug? Edit: I found a list of vulnerable sites on GitHub and checked all my critical sites. Everything I was really concerned with ...
21
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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 ...
21
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5answers
2k views

When hashing passwords, is it ok to use the hashed password as the salt?

I don't like this idea. But I can not come up with a technical argument against it. Can somebody explain it to me? The basic idea is: $passwd = 'foo'; $salt = hash($passwd); $finalHash = hash($passwd ...
21
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3answers
4k views

Doesn't plaintextoffenders.com just provide attackers with a good list of sites to attack for passwords?

On the face of it, PTO seems like a good idea in educating people about password security. On the other hand, if I were an attacker, PTO would be the first place I would start if I wanted to start ...
21
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4answers
2k views

What are spambots doing with unintelligible login attempts?

After constantly being under attack in phpBB, I created a new forum by hand, which successfully prevents spam bots from registering, and I get a report for every failed login attempt, telling me the ...
21
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6answers
4k 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 ...
21
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6answers
2k views

Is there a use-case that renders the password manager obsolete?

Background Trevor posed a question about the nature and validity of using a password manager, given the current prevailing model of authentication on most web resources. Caveat: this is not the ...
21
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7answers
2k views

My company policy states I must put all passwords in a password safe shared with management. Is this secure?

As the title says, my company has a policy that all passwords to e.g. our workstations and server logins must be stored in an online safe. I won't say which one but there are some out there you can ...
21
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5answers
5k views

What's the practical limit for rainbow-table based bruteforce?

Say we have a hash of a password. The password can be considered to be made of of totally random characters and has a fixed length of N. The hash is SHA1(password+salt), where the salt is of length M. ...
21
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5answers
1k views

Hashed password storage with random salt

Ever since I've been making sites that require a user to log in with a username and password I've always kept the passwords somewhat secure by storing them in my database hashed with a salt phrase. ...
21
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5answers
3k views

Is my bank storing my password in plain text? [duplicate]

My bank (and every bank I've come across) only ever asks for individual characters from my password when logging in. Is my bank storing my password in plain text?
21
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2answers
3k views

Sending temp password when users first registered - is that good for anything?

One of our clients has sent us a list of security requirements. One of them was that registration does not including setting a password - once complete, a temp password is sent to the user, and the ...
21
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6answers
33k views

How secure is WD MyPassport lock

I have a WD My Passport hard drive. There is an option that allows you to lock your hard drive with a password. How secure is this lock? They don't give details about the encryption algorith or the ...
21
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2answers
1k views

Can client-side hashing reduce the denial-of-service risk with slow hashes?

When storing user's passwords that you need to verify against (but not use as plaintext) the current state of the art is: Hash the password Use a salt Use a slow hash function - bcrypt, scrypt, etc. ...
20
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8answers
9k views

On two-step login forms, why is it the login name and not the password that's asked first?

There are several login forms (e.g. Google's) on the internet where you first enter your login name and then, once that's submitted, you get to enter your password. One of the advantages of this is, ...
20
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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 ...
20
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7answers
1k views

At what length does a password stop making sense?

I'm going to recommend that our users start using a password manager and start creating strong random passwords. Though I don't know what size of a password to recommend. Is it possible for a ...
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9answers
1k views

Is a simple, but very long password a good password?

Is a password like wwwwwwwwwwwwwwwwwwwwwwwww9 (25x 'w' and a number) secure? It would be easy to remember.
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5answers
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Why do some websites and programs restrict password characteristics?

There are some websites and even programs that I use that have rediculous password restrictions. Lots of forums for instance restrict passwords to ~32 characters. Others enforce a restricted charset. ...