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

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44
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8answers
7k 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 ...
44
votes
5answers
4k views

Is it safe to tell your users what kind of hashing algorithm you use?

For example, on the user registration page, is it safe to tell people "Your password will be stored as a one-way hash using the (whatever) algorithm."
44
votes
5answers
9k views

How can I know that developers will be ethical and not record my password in plaintext

I am not asking why hashing should be done. Instead, I want to know how to prevent that developers record user passwords to hack their user's other accounts, especially their email. Couldn't they ...
44
votes
3answers
8k views

Paypal sent an email addressing me with one of my old passwords as my name

I got this email from service@intl.paypal.com, with the title: Your account has been limited until we hear from you. I think this is a scam / spoof email because I don't see any notification in my ...
44
votes
6answers
4k views

Is the option to jump to blanks in password fields a security risk?

Using Ctrl + ← / →, it's a common behavior across different operating systems to jump from word to word (or from blank to blank) in text input fields. Now I've discovered that this also applies on ...
44
votes
9answers
6k views

Can users make use of a password manager when banks tell them never to write passwords down?

Consider a user who wants to use a password manager for their banking passwords. Advice from banks usually says they should never write down their password. The user would be concerned about going ...
44
votes
1answer
3k views

What's the risk if I accidently type my password into a username field (Windows logon)?

I'm used to logging into my personal Mac which is a password-only field (like waking from sleep mode). Sometimes I have to use a Windows network on which I have an account, but of course I have to ...
43
votes
9answers
4k views

Isn't OAuth, OpenID, Facebook Connect, and others crazy from a security standpoint?

I work with APIs all the time and I work with web developers who insist that OAuth, OpenID, etc are far superior than a home-brew method. Every site seems to be using these as well now for ease of use ...
42
votes
4answers
6k views

Is it good practice to ban an IP address if too many login attempts are made from it?

Since an IP address does not necessarily represent a specific device, but probably a whole network/company/etc. does it at all make sense to block an IP address if there is a significant amount of ...
41
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9answers
11k 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?
40
votes
7answers
3k views

“Real” Salt and “Fake” Salt

During a Q&A period at DEFCON this year, one member of the audience mentioned that we're using "fake salt" when concatenating a random value and a password before hashing. He defined "real salt" ...
39
votes
7answers
8k views

Why isn't open WiFi encrypted?

As far as I understand, WiFi networks that require no password send traffic through the air unencrypted. Those that require a password encrypt each connection uniquely, even if they're all using the ...
39
votes
5answers
8k views

Are GUIDs safe for one-time tokens?

I see a lot of sites use GUIDs for password resets, unsubscribe requests and other forms of unique identification. Presumably they are appealing because they are easy to generate, unique, ...
39
votes
2answers
5k views

Pre-hash password before applying bcrypt to avoid restricting password length

Good practice is not to unnecessarily restrict password length, so that appropriately-long passphrases (perhaps 35-45 chars for 6/7 dicewords) can be used. (See e.g. Should I have a maximum password ...
39
votes
3answers
4k views

Security Review - password_hash implementation for PHP

I'm currently working on a "helper function" for PHP's core to make password hashing more secure and easier for the majority of developers. Basically, the goal is to make it so easy, that it's harder ...
37
votes
8answers
4k views

Why improvising your own Hash function out of existing hash functions is so bad

I'm afraid I'll have tomatoes thrown at me for asking this old question, but here goes. After reading that cooking up your own password hash out of existing hashing functions is dangerous over and ...
37
votes
11answers
30k views

Are password-protected ZIP files secure?

Following my answer. If I can list contents of password-protected ZIP file, check the file types of each stored file and even replace it with another one, without actually knowing the password, then ...
37
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 ...
36
votes
10answers
5k views

Is there any point in using 'strong' passwords?

Let's say I'm setting up a new account on a website. Should I bother using a strong password? My reasoning is this: Password strength is a rough measure of how long it would take to brute-force my ...
35
votes
15answers
6k views

Why do people think that this is bad way to hash passwords?

Well, please tell me, what's wrong with this code: $password = "hello"; $password = md5($password); for($i=1;$i<20;$i++){ $password = md5($password); } It's exactly the same as this one: ...
35
votes
3answers
2k views

Am I wrong to believe that passwords should never be recoverable (one way hash)?

I recently forgot my password for our cable provider online account, only to discover that they sent it to us via plain text in an email. I quickly sent an email to customer support asking them if ...
35
votes
10answers
3k views

Is there a method of generating site-specific passwords which can be executed in my own head?

I was thinking recently about password security. My goal is to have mostly random passwords, that are different for each site. But you also should be able to remember them (or re-generate them) ...
34
votes
11answers
6k views

Is it good practice to send passwords in separate emails, and why?

I have heard from different people and in different places that if I send an encrypted file to someone else, I should send them the password in a separate email; but why? If someone is sniffing, they ...
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 ...
34
votes
4answers
2k views

If email is insecure, why do we use it for password resets?

I found myself telling a coworker today "Email is insecure, that's why we developed our secure report application." But then it struck me, Why is email considered insecure? If it is so insecure, why ...
33
votes
7answers
9k views

Is salting a hash really as secure as common knowledge implies?

(I did search on this topic, but I found no complete question/answer that addressed it, or even good portions of questions that might be relevant.) I'm implementing a salt function for user passwords ...
33
votes
4answers
2k views

Why did my provider reset my password after someone else attempted to gain access to my account?

Recently a provider (of SIP trunking services) I subscribe to sent me a strange email. It claimed that someone in another country attempted to reset the password to my account and was unsuccessful in ...
32
votes
8answers
5k views

Why must I have a “strong” password for sites like this? [duplicate]

I don't share any personal information with StackExchange, I'm not really worried about anyone trying to hack my account and I can't see any incentive for them to do so, and yet the password strength ...
32
votes
7answers
11k views

How can crackers reconstruct 200k salted password hashes so fast?

I'm researching for a small talk about websecurity and I found one article about the formspring hack, which made me curious. They claim to have used SHA-256 + salt We were able to immediately fix ...
32
votes
1answer
5k views

Are there more modern password hashing methods than bcrypt and scrypt?

This question made me start thinking about password hashing again. I currently use bcrypt (specifically py-bcrypt). I've heard a lot about PBKDF2, and scrypt. What I'm wondering is if there are any ...
32
votes
2answers
3k views

Why does Google cripple the 2FA Google Authenticator PAM module?

If you enable 2FA for Google Apps the shared secret is 160 bits. The google_authenticator PAM module on the other hand seems to use 80 bits for the shared secret. According to RFC 4226: R6 - The ...
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
8k views

Why are brute-force password-cracking attacks not automatically detected and thwarted?

Why doesn't software automatically detect password-cracking attacks, and thwart them? Long version: Suppose that someone tries a brute-force password-cracking attack on some program XYZ that ...
31
votes
5answers
6k views

If a web site shows me what my password was changed to, is it stored as plain text?

I just changed the password on a school-related web site. After completing the change successfully, the next page showed what the password was changed to. Can I conclude from this that the password ...
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 ...
31
votes
6answers
3k views

Does verifying identity by positions in passwords mean passwords are stored unhashed? [duplicate]

If authentication occurs by asking the user for the characters at certain positions in the password (such as: give the 3rd and 7th character in the password), does this imply that passwords are stored ...
31
votes
8answers
5k views

Is it safe to use leakedin.org?

leakedin.org claims to offer a service checking if your LinkedIn password has been stolen and whether it has been cracked. The website claims that it's pure Javascript, that is your password won't ...
31
votes
4answers
16k views

Standards for encrypting passwords in configuration files?

My workplace has a standard that plaintext passwords are not allowed in application configuration files. This makes enough sense on its face, in case someone gets access to the config files they ...
30
votes
3answers
2k views

Changing picture as characters entered into password

When Lotus Notes asks for the password, it displays a screen with a picture that appears to change after a new character is entered after the fifth character. I have noticed the sequence of ...
30
votes
6answers
8k views

Length of passwords that are rainbow table safe

With large computing power (like what you can get in the Amazon cloud for example) you can generate huge rainbow tables for passwords. There also seems to be some large rainbow tables reachable that ...
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 ...
30
votes
9answers
19k views

Feeding /dev/random entropy pool?

Which way of additionally feeding /dev/random entropy pool would you suggest for producing random passwords? Or, is there maybe a better way to locally create fully random passwords?
30
votes
5answers
2k views

What are the security implications of storing password blacklist?

I want to add a password blacklist that would prevent the 1000 most common passwords from being used in order to mitigate shallow dictionary attacks. Is there any negative implication of storing this ...
30
votes
7answers
2k views

How do I educate others about social engineering?

One of my friends used to boast about how long his passwords are. One day, I decided to play a prank and social-engineered it out of him. I was pretty surprised as to how effortless the entire ...
30
votes
2answers
9k views

I just send username and password over https. Is this ok?

When a user's logging in to my site, they send their username and password to me over https. Besides the ssl, there's no special obfuscation of the password - it lives in memory in the browser in the ...
30
votes
2answers
11k views

HMAC - Why not HMAC for password storage?

Nota bene: I'm aware that the good answer to secure password storage is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. Let's say ...
29
votes
8answers
5k views

Why would salt not have prevented LinkedIn passwords from getting cracked?

In this interview posted on Krebs on Security, this question was asked and answered: BK: I’ve heard people say, you know this probably would not have happened if LinkedIn and others had salted ...
29
votes
7answers
4k views

Do non-keyboard characters make my password less susceptible to brute forcing?

I can put characters in my password for which there are no keys on a keyboard. On Windows, Alt+#### (with the numpad) inserts the character for whatever code you type in. When I put this in a ...
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 ...
28
votes
3answers
3k views

Is there any advantage to splitting a password?

I've been reading about the LANMAN (LM) hash and I'm curious about a particular part of the algorithm. The LM hash is computed as follows: The user’s ASCII password is converted to uppercase. ...