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

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3answers
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Password manager vs remembering passwords

I have always thought that you are not supposed to use a password manager but to keep your passwords in your head, but lately I have thought about the pros and cons of having a password manager. Some ...
27
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2answers
1k views

Does versioning an encrypted file make it less secure?

Suppose I use KeePassX as a password manager, and I store the kdb file in Sparkleshare folder as a way for backing up and syncing with multiple devices. The kdb file in itself would be encrypted, but ...
27
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3answers
4k views

MD5 collision attacks: are they relevant in password hashing?

DISCLAIMER: This is not an endorsement of MD5 as a password hashing function. I know about parallelization, GPUs, and dedicated password hashing functions like bcrypt and scrypt. With that out of ...
26
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6answers
7k views

Are passwords that are manually typed in really unrecoverable from memory or disk?

As part of an increase in the security measures for our company, we're moving to making sure all password logins (databases, servers, etc), are done through a password prompt and never using stored ...
26
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8answers
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Why is password hashing considered so important?

After reading this article, I can see the benefits of password hashing as a second layer of defence, in the event of an intruder gaining access to a password database. What I still don't understand is ...
26
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5answers
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How does storing hash passwords work? [duplicate]

In usual network applications, that employ password hashing, is the user password hashed on client side before sending it to the server, or is it sent without hashing as encryption of plain text ...
26
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3answers
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For an HTTPS web application, is it worthwhile to encrypt the password before POSTing it, to keep a MITM attacker from harversting it?

Our application has recently gone through penetration testing. The test found one critical security breach, which is essentially: The problem: Attacker sets up a WiFi spot. User enters our site ...
26
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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
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2answers
20k views

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 ...
26
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5answers
5k views

Security impact of using a public password for free WiFi

We have a WiFi network that we want to be public and free. Does having a password that is known to everyone provide any additional security advantage to the people using this network as opposed to ...
26
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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 ...
26
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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 ...
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5answers
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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 ...
26
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6answers
3k views

Are there secure alternatives to single-use password reset links?

We currently have what I believe to be a pretty standard scheme for dealing with password resets. Our reset links are single-use links: They expire immediately after they've been visited, even if the ...
25
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10answers
7k views

Two passwords for one account

Would it be a good idea if you had one account which would require two different passwords ? For example your login details were: email: example@gmail.com password 1: P4$$w0rd1 password 2: ...
25
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4answers
4k 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 ...
25
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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 ...
25
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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 ...
25
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6answers
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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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10answers
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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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8answers
23k 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 ...
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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4answers
6k 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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10answers
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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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3answers
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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 ...
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
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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 ...
24
votes
5answers
989 views

Would turning a Diceware phrase into a sentence decrease its security?

Diceware passphrase lengths are on the rise - up to six or seven words now. The old adage that passphrases are easier to remember may be true for shorter phrases, but six truly random words can be ...
24
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5answers
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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 ...
24
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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. ...
23
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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 ...
23
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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 ...
23
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4answers
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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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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 ...
23
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2answers
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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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4answers
7k 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 ...
23
votes
4answers
12k 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 ...
23
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5answers
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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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4answers
2k views

Should I be worried if I accidentally entered my password in a username field?

Occasionally I will fail to hit Tab properly when entering a username/password combination. This results in me submitting username "myUsername$ecretPa$$word" along with a blank password. I always ...
23
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1answer
7k views

Can a dictionary attack crack a Diceware passphrase?

Everyone knows the words used in Diceware passwords (all 6^5 = 7776 words are published) -- they're all common words. Everyone seems to know that we're not supposed to use dictionary words for ...
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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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 ...
22
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3answers
3k 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
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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 ...
22
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5answers
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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 ...
22
votes
4answers
5k 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
votes
2answers
4k 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 ...
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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6answers
36k 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 ...
22
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3answers
2k 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 ...