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

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14
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11answers
3k views

Best practice for password distribution

I am about to set up a new account on my Linux server for a user that lives in another state in the U.S. I can't think of a good way to get them this user their password. There must be a standard ...
35
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 ...
32
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 ...
26
votes
12answers
4k 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
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 ...
15
votes
2answers
3k 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 ...
15
votes
3answers
529 views

Is it OK to tell your password to an admin? [duplicate]

Possible Duplicate: From a security point : Is it OK to tell your password to an admin? I am working in a small company (20 employees) as a senior SW engineer. After having some email ...
10
votes
8answers
2k views

What chars should I not allow in passwords?

I am planning to develop a website that require that the users register a username and a password. When I let the user choose a password, what chars should I allow the users to have in the password? ...
9
votes
3answers
2k views

How can I mitigate the threat that DPAPick poses to my DPAPI protected data?

The Windows Data Protection API (DPAPI) is the suggested method for storing secrets on Windows systems (such as database passwords required by ASP.Net applications). DPAPick was presented at BlackHat ...
8
votes
3answers
4k views

How often do two users use the same password

If no two users use the same password, then in theory salting the password hash is not needed. How often, in practice, do two users have the same password?
7
votes
3answers
14k 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 ...
7
votes
4answers
916 views

Why using random salts?

I read this blogpost on how to store passwords in a database, the secure way. Elbert tells us to do this: Generate a random salt and include something random and the username in it. Hash this. Hash ...
6
votes
4answers
1k views

Password entropy in layman's terms

Entropy is a term used often in relation to password security and brute-force attacks, but it is a topic that can get complicated quickly. What is the best way to describe password entropy (what it is ...
3
votes
2answers
2k 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 ...
46
votes
8answers
3k views

I'm an IT consultant. Should I discourage a client from telling me his password?

I'm an IT consultant. One client has known me for a few years. He wants me to do some work on his kids' laptop again. I'll need to log into his kids' Windows user account. (I'm guessing that multiple ...
23
votes
5answers
2k 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 ...
14
votes
2answers
2k views

How many passwords does the average user know?

Looking for research on the count and complexity of passwords that an average user is actively using. Note: Also, just to be clear, by research, this is not a request for you to respond with an ...
14
votes
4answers
9k views

Is it possible to securely store passwords using reversible encryption?

Everyone says that you need to use a non-reversible hash when you store passwords so that even if your database is leaked, the passwords themselves are still safe. I'm wondering if there is anyway to ...
10
votes
3answers
386 views

If multi factor authentication is enabled, how should that affect self-service password reset?

Given that security is only as secure as its weakest link, suppose I have website with additional authentication enabled in any of these ways: (example, multiple conditions may be required) ...
8
votes
3answers
1k views

Is this code snippet good enough for password hash and salt

After a few days reading up about salting and hashing passwords, I found an actual bit of code that tells how to do it. This is what I found: $blowfish_salt = ...
8
votes
3answers
7k views

Choosing a session ID algorithm for a client-server relationship

I am developing an application which has a client-server relationship, and I am having trouble deciding on the algorithm by which the session identifier is determined. My goal is to restrict ...
8
votes
3answers
1k views

time to crack file-encryption password - more than just iteration

I have often seen that takes x amount of time to crack a certain length password. But this just seems to be the amount of time it takes to iterate through all the possibilities. What about the time it ...
8
votes
2answers
849 views

Stretching a hash, many iterations versus longer input string

I have been reading up on various password hashing schemes, for example the SHA-based Crypt proposed by Ulrich Drepper and used in some Linux versions. A recurring theme here is to 'strengthen' or ...
7
votes
4answers
6k views

How do online accounts get hacked?

How does your typical users run-of-the-mill Facebook/twitter/gmail/AIM/etc account get hacked? Is it simply a matter of a weak password? Are they typically the victim of phishing or other social ...
5
votes
1answer
2k views

Practices for storing username/password in Web applications

I have read the following question: Storing password in Java application but I don't find the answers useful for my case. So here is my question somehow related to that. I have a Java Web application ...
5
votes
3answers
20k views

Four-way Handshake in WPA-Personal (WPA-PSK)

Can someone explain to me in what consists the Four-way Handshake in WPA-Personal (WPA with Pre-Shared Key), which informations are being sent between AP and client, how is it possible to find the AP ...
5
votes
4answers
4k views

Brute force vs other methods of recovering passwords from shadow file

Do you know any good approach for de-hashing/actually bruteforcing hashed passwords in the shadow file? On various operating systems, any good solutions/methods/programs. Or is it better to upload ...
18
votes
6answers
2k 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 ...
14
votes
6answers
700 views

Is there additional security value in using passwords with words or phrases in non-English languages?

I was thinking about correct horse battery staple. I am not a native English speaker. In my language, the above could be written as: vqrno kon bateriq telbod OR вярно кон батерия телбод. Keep in ...
13
votes
2answers
373 views

Concrete figures on password cracking in the wild

While password guessing is a science, not every attacker out there is up-to-date with the latest advances or cares to invest in GPUs or FPGAs. It's easy enough to test online password guessing ...
13
votes
6answers
1k views

Does prepending a salt to the password instead of inserting it in the middle decrease security?

I read somewhere that adding a salt at the beginning of a password before hashing it is a bad idea. Instead, the article claimed it is much more secure to insert it somewhere in the middle of the ...
12
votes
3answers
2k 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 ...
11
votes
3answers
2k views

Additional security of keyfile on top of a master password for KeePass

I use KeePass + Dropbox to manage and synchronize my passwords across my devices. This system works really great and I trust KeePass' security model. However my biggest remaining concern is the ...
10
votes
7answers
2k views

Does adding dictionary words to passwords weaken them?

This might sound like a stupid question, but hear me out. If I'm encrypting my financial information and sensitive data via a program like TrueCrypt, the strength of the password is going to matter a ...
9
votes
3answers
1k views

Logging “password with counter” use

When prompted to update their passwords after they've become stale (whether that's after 30, 60, 90 days — whatever is implemented by policy), many users simply increment the number that they may have ...
9
votes
2answers
1k views

How does Google not care about “spaces” in Application-specific passwords?

I have recently setup "2-step verification" for my Google account. One of the features is the ability to create "Application-specific passwords " for devices that do not support the 2 step process. ...
8
votes
5answers
509 views

Utility company does not hash passwords in the database

I had to use my utility company's online account information application and forgot the password. Going through the steps of resetting the password I was emailed the password in the open. I found this ...
7
votes
4answers
2k views

Password Vault - Enterprise

I want to be clear from the get-go that I am NOT looking for a user password management solution. My organization already uses AD for that. What I am looking for is a password vault. Up until now, ...
7
votes
4answers
3k views

How to implement a “Remember me” on a mobile app?

I would like to implement a "Remember Me" time-limited auto-login type feature on a mobile application (on Android). To start the app, the user must type in a username and password. For convenience, ...
6
votes
2answers
806 views

How should I make diceware passphrases more memorable?

I find that truly random diceware passphrase, more often than not, either contain a word that is easily misspelled or has an order that is illogical. I think there are three ways to make a diceware ...
5
votes
1answer
496 views

Chinese or “pinyin” wordlists for dictionary attacks

Background: I am currently trying to crack a salted md5 hash which I have recovered from an embedded device running busybox and manufactured in china. I have tried john the ripper using all of the ...
5
votes
1answer
428 views

Should password hashes be encrypted or HMACed?

Assume I am hashing user passwords with PBKDF2, bcrypt, scrypt, or some other secure key derivation function. Are there: tangible security benefits, precedents, and respected research for ...
5
votes
1answer
908 views

Bcrypt as a key derivation function?

I read a lot of entries at stack exchange about bcrypt and why it is supposed to be better than PBKDF2 in terms of password storage. I'm asking now if bcrypt is better than PBKDF2 in terms of key ...
4
votes
2answers
541 views

user authentication by decrypting a random blob

Normal user authentication is done by comparing "hash"-values. A simple example of this: The user password is hashed with PBKDF2 on the client using a salt (the salt is the hash of the user password ...
4
votes
4answers
2k views

Are there lists of most common words or ngrams used in passwords and passphrases?

I've been thinking about ways to focus brute forcing dictionary attacks on passwords and passphrases based on the assumption that certain words, combinations of letters, and combinations of words are ...
3
votes
2answers
277 views

Is it really “Time to add a word” if there are no tools to crack passphrases of 3 words and up?

It's "time to add a word" says Arnold Reinhold, the creator of Diceware, in his blog (3/2014). He advices to use 6 word sentences (or 5 words with one extra character chosen and placed at random) from ...
3
votes
3answers
678 views

Encrypting passwords?

I am planning on creating a text file to store my passwords, so I only need to remember 1 password (at the moment, I have about 20 long/complex passwords in my mind, and am worried that I might forget ...
3
votes
4answers
567 views

Best practice for forgot password form, ok to leak that a given e-mail is invalid

On our forgot password reset form, is it ok to leak that a given e-mail address entered is invalid? Or should we always just return success and check your e-mail, even if the e-mail is not valid. I ...
3
votes
3answers
891 views

Best password storage scheme for high entropy, unique passwords which is failure resistant [closed]

What is the best, most secure, easiest way to: store unique, strong passwords for every service which requires authentication make the system resistant (total loss of security is avoided, breaches ...
1
vote
3answers
311 views

Logic for generating Strong Password?

I try to encrypt password using MD5 but there are decoders for MD5. So I'm worried about encryption of password for big website. Is there any logical suggestion or step function to generate strong ...