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

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Is AES encrypting a password with itself more secure than SHA1?

This isn't really a practical question, but more a question of curiosity. I heard a CS professor recommend stepping up from md5ing passwords not to SHA1, but to AES encrypting the password using ...
21
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4answers
2k 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 ...
21
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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 ...
21
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2answers
15k 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 ...
21
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6answers
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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 ...
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3answers
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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 ...
21
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5answers
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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
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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?
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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 ...
21
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2answers
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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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2answers
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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 ...
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5answers
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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 ...
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5answers
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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 ...
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9answers
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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. ...
20
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4answers
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How is Gmail susceptible to brute-force attacks?

In the Atlantic article "Hacked!" it says: My wife’s password was judged as “strong” when she first chose it for use with Gmail. But it was a combination of two short English words followed by ...
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4answers
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Google Account: implications of using application-specific passwords

In the wake of the recent Mat Honan story I decided to try out two-factor authentication on my Google account. But in order to keep using it with Exchange, the Android OS, Google Talk and Google ...
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5answers
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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. ...
20
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1answer
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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
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4answers
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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 ...
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4answers
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How secure is Snowden's MargaretThatcheris110%SEXY password?

In an extra from Edward Snowden's interview with John Oliver, Snowdon advises that a good password to use is one such as MargaretThatcheris110%SEXY.. Also, on the Errata Security blog, Robert Graham ...
19
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8answers
17k 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 ...
19
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4answers
953 views

Should I be concerned when a “Forgot Password?” tool sends my password in plaintext?

Some sites I have been a member of in the past don't go through the normal "Forgot Password?" process. Instead of e-mailing me a unique password reset link or something of the like, I have received ...
19
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4answers
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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 ...
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5answers
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Is it alright to tell everyone your encryption information?

I have an account in an online banking system and they have the FAQ with something like this: How secure is the <Online Banking System Name>? Each page you view and any information ...
19
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6answers
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Hash function change

I have user account passwords stored in a database using an unsafe (old) cryptographic hash function. What is the best/usual approach to changing password hash function? Only two ideas come to my ...
19
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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 ...
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4answers
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Is it a bad idea for an information holder to e-mail a user their password?

A couple of websites with which I'm registered have, after a period of inactivity on my part, each sent me an e-mail to remind me that I'm still registered. In each case, that e-mail has included my ...
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3answers
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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 ...
18
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6answers
3k views

Why do we ask for a user's existing password when changing their password?

In a web applications context, when a user wants to change their current password, generally they would have to enter their current password first. However at this point, the user has already been ...
18
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3answers
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Router password vs MAC filtering?

I just bought a Galaxy S4, and it didn't connect to the WIFI in my house (I have a 14$ router). After a bit of testing, I've decided to leave my connection open without a password, but added the ...
18
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2answers
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Why is it always `HASH( salt + password )` that we recommend?

Browsing over this site, many forums, online articles, there's always one specific way we're suggesting to store a password hash: function (salt, pass) { return ( StrongHash(salt + pass) ) } But ...
18
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4answers
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Should I implement incorrect password delay in a website or a webservice?

With arguments expressed in this answer, there is a few seconds delay between user enters an incorrect password and when he/she actually learns, that password was incorrect. This security solution is ...
18
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7answers
895 views

Are common passwords at particular risk?

The question Should we disallow common passwords like “password” and “12345”? on User Experience immediately made me think that these common passwords were extremely dangerous not because they are ...
18
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4answers
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Deleting a Java Object securely

I know that in order to delete a Java object I should use character array instead of String, since I can safely erase (rewrite the character array with other data) its content. This seems not to be ...
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6answers
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How to avoid scripts with hardcoded password? [duplicate]

I have some scripts on Ubuntu Linux machine that logs in to a database server to run some maintenance daily. To login to the database, I need a password and right now it is hardcoded in the script. ...
18
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5answers
933 views

Is there any legal reason to save a cleartext password?

I called customer service of a well known company and discovered that the operator had the ability to view my website password in clear text on her screen. I asked her about this and she defended the ...
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4answers
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Password resets - what practices should web services follow?

Many of you may have seen How Apple and Amazon Security Flaws Led to My Epic Hacking, where a Wired reporter's Amazon, Apple, Gmail, and Twitter accounts were successfully hacked. The hacker followed ...
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4answers
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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 ...
18
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3answers
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MySQL OLD_PASSWORD cryptanalysis?

The password hash used for MySQL passwords prior to version 4.1 (now called OLD_PASSWORD()) seems like a very simple ad-hoc hash, without salts or iteration counts. See e.g an implementation in ...
18
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1answer
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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
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2answers
786 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. ...
18
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1answer
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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 ...
18
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1answer
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How to apply a pepper correctly to bcrypt?

Update: There is a better way to add a server side key, than using it as a pepper. With a pepper an attacker must gain additional privileges on the server to get the key. The same advantage we get ...
17
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5answers
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From a security standpoint should users be asked to confirm their password when registering?

Is it advisable to have users re-type their password to confirm it's correct? On User Experience the general consensus seems to be no but I'm wondering if this has security ramifications? EDIT: my ...
17
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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 ...
17
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6answers
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Appropriate password requirements for a login (OpenID) service/provider/delegate/thing

This is with regards* to Stack Exchange's upcoming OpenID provider (and in particular, discussion about password requirements). Currently, password requirements are: Must contain 3 of: lower case ...
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7answers
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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 ...
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3answers
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Password in file .php

My connection.php file stores the credentials to connect to the database. <?php $objConnect = mysql_connect("localhost","username","password"); mysql_select_db("selectDB", $objConnect); ...
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4answers
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How to treat non-optional bad security questions?

Every once in a while I have to set up an account on a site that, while apparently at least not storing my password in plaintext, still force me to choose from a limited set of security questions that ...