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

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20
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6answers
2k views

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 ...
36
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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 ...
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 ...
28
votes
2answers
6k views

Does bcrypt have a maximum password length?

I was messing around with bcrypt today and noticed something: hashpw('testtdsdddddddddddddddddddddddddddddddddddddddddddddddsddddddddddddddddd', salt) Output: ...
21
votes
12answers
3k 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 ...
20
votes
8answers
18k 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 ...
15
votes
2answers
4k views

What's wrong with storing private keys in the cloud?

I know this sounds like a dumb question, but whats wrong with it? Assuming that all private data is encrypted (by the client) using PBE AES256, then is this scheme more vulerable than storing keys on ...
13
votes
3answers
719 views

How to manage team passwords?

How do most teams handle the storage of passwords, in particular the required changes when team members leave ? Right now, we use a centrally stored encrypted file but the thought of changing 100's ...
12
votes
3answers
509 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 ...
4
votes
11answers
4k views

Definitely safest password storage scheme?

I already asked this on StackOverflow but I was suggested this would be a better suited place and I found no way to "move" the question so I have to copy it. Believe, I know, there are hundreds ...
22
votes
4answers
7k 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 ...
16
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5answers
3k views

The AES Crypt implementation hashes a password 8192 times to generate the key. Is this necessary?

I'm considering encrypting some small files (hundreds of kb apiece) using the AES Crypt reference implementation. Looking at the source, it seems that the encryption key is derived from the IV and the ...
15
votes
8answers
1k views

Password management/synchronization?

Is there a good enough service I could run on my own home (Linux) server that I could use for storing/accessing/synchronizing passwords so they could be available for me from multiple ...
14
votes
4answers
1k views

How are browser saved passwords vulnerable?

Most browsers offer to save the password after entering it on many logon pages. What types of vulnerabilities are there for such saved passwords. I'm interested in what ways malware on web pages ...
9
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 ...
6
votes
2answers
6k views

How weak is MD5 as a password hashing function ?

A professor told us today, that MD5 is weak. I understand his chain of thought but pointed out, that IMHO MD5 is a good way to go if you would use a long (even really long) dynamic salts and static ...
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 ...
21
votes
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 ...
21
votes
2answers
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 ...
20
votes
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.
19
votes
3answers
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 ...
18
votes
2answers
5k views

How big should salt be?

I will be using scrypt to store passwords in my application. As such, I'll be using SHA-256 and Salsa20 crypto primitives (with PBKDF2). Having that in mind, how big salt should I use? Should it be ...
14
votes
2answers
1k views

Password and Generated number - How does it work?

In my company, they don't allow accessing the company email or servers from outside the company network. To access the email from outside the network, you have to use: Username, password and a number ...
3
votes
1answer
491 views

Perfectly Robust Hashing Scheme, or Completely Over-Engineered?

This is going to get long, so prepare. Basis of the question is, Do all these steps improve security, or am I completely overthinking the problem? Are my assumptions/thought process valid? We all ...
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 ...
7
votes
3answers
642 views

Can cloud based password managing services be trusted?

I'm a big time user of cloud based password managing services like LastPass. But in the light of recent revelations like various government backdoors in popular sites, programs like prism, etc. I'm ...
6
votes
2answers
7k views

Is it possible to speed up WPA/WPA2-PSK cracking using a rogue AP?

We know that WPA/WPA2-PSK uses a PTK (Pairwise Transient Key) for each client to encrypt the communication. This PTK is generated through the process known as 4-way handshake. As told in the related ...
5
votes
3answers
587 views

Is piping a `ssh-agent` signed message as a password secure?

There's an encrypted filesystem on a server I ssh into using public key authentication. Since a forwarded ssh-agent can deterministically sign a message (see also the ssh-agent protocol section ...
27
votes
8answers
2k views

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 ...
21
votes
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. ...
14
votes
2answers
1k views

Are there some good papers (or discussions) on using Markov chains or Hidden Markov Models for password auditing/cracking?

As a programmer and language enthusiast I've been very interested in Markov chains for some time. Considering the influence of natural language on password and passphrase selection (by humans of ...
10
votes
1answer
327 views

Is this cross-site password model secure?

I'm looking for a way of securely having passwords for different pages. Say I generate this password: ild23rfsfdfg%*#fArg34t34657%537@asd7oak2094^*q2k2k@Kk3j4tn453Q5# Then, for each site, I change ...
8
votes
2answers
565 views

Banning specific passwords?

There have been a couple of questions about enforcing good passwords, so I thought I'd add my own: In addition to enforcing a minimum Shannon entropy, would it generally be a good practice to ...
4
votes
8answers
552 views

Does it take longer to brute force a password starting with z than one starting with a?

I was wondering about the following: If someone tries to get my password with Brute Force, will a password starting with "a" guessed faster than one starting with "z" ? In this case assume the ...
4
votes
1answer
105 views

How to help users manage password portfolios based on risks of compromise?

A framework for modeling password management risks and costs, and the beginnings of a good strategy for users to help them manage passwords for their often large portfolios of accounts is outlined in ...
4
votes
5answers
4k views

Password reset links: random value or authenticated message?

Which is better? Create tamper-proof encrypted password reset token which contains the user id and the expiration time within the encrypted token. Generate a random token and store it in the ...
4
votes
4answers
903 views

Store a password to avoid user interaction

I am creating a windows service that sends email to a user. It uses a Gmail account to send the email, so it needs a password to access the account. It also needs to do this automatically, without ...
3
votes
1answer
228 views

Security of Windows Screen Saver Password

How secure is the Windows screensaver password? Seeing that screen saver passwords are used in the corporate world, is there any way of bypassing the screen saver after it is already running? Could a ...
17
votes
7answers
1k views

Taking password letters not whole one, is this secure? [duplicate]

I found a site which is taking password letters from their users not the whole password. Is this secure? Or do they have saved password as salted hash (MD5)?
13
votes
3answers
1k views

What is a good enough salt for a SaltedHash?

Since I'm hashing all passwords with each their own salt, is there a benefit to the salt being really random, or would an incremental counter or a guid be good enough? Also, is there a benefit of ...
9
votes
4answers
1k views

Reasonable way to store encrypted passwords in a webapp's database, Linux

This question is generally similar to past questions asked here, but I haven't seen one the relates to Linux. Case at hand: a PHP web app has a MySQL backend. As part of its functionality it accesses ...
9
votes
4answers
703 views

Password security

I was requested at the login page of a website to first change my password. After typing in a new password, the web page told me the new password did not differ enough from the previous one. Does this ...
9
votes
2answers
779 views

Plain Text Password Reset Vulnerability

If I receive an email with a plain text generated password (in response to a password reset request), is this a vulnerability? The password expires after one use, in other words the user has to change ...
8
votes
3answers
2k views

Is it safe to generate passwords online?

I usually generate strong passwords using various online tools. Some time ago I mentioned it to friend of mine and he looked at me as if my life was one big fail. Is it really so unsafe to generate ...
8
votes
1answer
475 views

Protecting emails in your database

It's common to encrypt passwords in the database, but I'm wondering what solutions are out there to protect emails in your database. Not just from hacking, but from disgruntled employees or engineers ...
7
votes
2answers
232 views

Does password-hashing “busy-work” need to be cryptographically secure

All modern password hashing schemes are deliberately designed to include a huge amount of "busy-work", to limit the speed with which an attacker would be able to conduct password hashing attempts. ...
7
votes
5answers
946 views

Is including a secret GUID in an URL Security Through Obscurity?

I know that this question is a little bit on the side of Opinion/Discussion, but I think there's a provable answer to it. I think the common view of "Security Through Obscurity" is that the security ...
7
votes
1answer
4k views

Does NIST really recommend PBKDF2 for password hashing?

We hesitated between BCrypt and PBKDF2 for password hashing. In many forums and blogs people say something like "In their Special Publication SP 800-132 NIST basically recommends using PBKDF2 for ...
6
votes
2answers
2k views

Considering that SRP is better than SSH and Basic Auth, how can it be implemented in a website?

SRP is short for Secure Remote Password protocol, and provides a better way for passwords to be sent over the internet. I've read the information at it's Stanford University home page, the Wiki ...
6
votes
4answers
5k views

Are the iPhone “connect the dots” passwords secure?

A popular way to login to iPhones and other phones is to use a "connect the dots" password. For those unfamiliar, it looks something like this: Is this kind of passwords secure from brute force ...