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

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248
votes
18answers
36k views

How does changing your password every 90 days increase security?

Where I work I'm forced to change my password every 90 days. This security measure has been in place in many organizations for as long as I can remember. Is there a specific security vulnerability ...
1
vote
0answers
44 views

Lock Windows to a specific app

Is it possible, using some program or application, to lock Windows 7 so only a specific app can be used, for example Word, until a password is entered? Thanks!
2
votes
1answer
148 views

How was the Xbox One password verification compromised?

So, we have this article: http://www.engadget.com/2014/04/04/xbox-live-five-year-old-hacker/ Apparently, using nothing but spaces the local account (with an obviously saved password... I hope) was ...
6
votes
4answers
199 views

Relationship of password strength and key strength

I have just started educating myself about cryptography, and while it is mostly making sense, a few things are still eluding me. One being: In systems that take a user's pass-word/-phrase in order to ...
2
votes
1answer
56 views

Safety while ciphering data

Say I wanted to encrypt some sensitive information with a symmetric algorithm using a program on a computer. Is it possible that a hacker could retrieve the data,salt, iteration, cipher, keysize while ...
1
vote
2answers
106 views

How could police identify digital contraband and charge someone if it's encrypted with keys?

For example, say I am transferring heavily-encrypted DVD/Blu-ray movies/game copies over the internet. However, I am using double or (+) encryption with keys required to decrypt the file using an ...
0
votes
1answer
72 views

Is using MD5 in NTLMv2 protocol to store Windows passwords is secure?

I read that Windows (probably not new OSs but say, Windows Server 2008) stores passwords using Hashes using NTLMv2 protocol which uses MD5 hash function. My questions: MD5 is known to be insecure ...
-3
votes
0answers
25 views

How many possible combinations in 8 character password? [migrated]

I need to calculate the possible combinations for 8 characters password. The password must contain at least one of the following: (lower case letters, upper case letters, digits, punctuations, special ...
-3
votes
1answer
29 views

How many possible symbols and punctuations in a password? [closed]

I want to compute the possible combinations of a password consists of 8 digits of: alphabetical letters (26), numbers (0-9), symbols and punctuations. In order to compute this, I have to know the ...
0
votes
2answers
84 views

How many bits of entropy should I aim at for my password? [closed]

I mainly use 2 passwords: 1 is a 4 word full lowercase passphrase of 18 letters long which I use wherever possible. The other is basically 3 words and a digit with the first word in full uppercase and ...
1
vote
2answers
93 views

How can I analyze password recovery tokens?

All websites that support authenticated user interactions have a password recovery feature. Usually they will email the password reset link through which you can easily recover your account by typing ...
2
votes
1answer
79 views

Locality Sensitive Hash (LSH) function to approximately match old passwords

Recently, I ran across a website that requires me to change my password after X number of days had passed since I had last created one. Intelligently, the service made sure that the password did not ...
0
votes
2answers
299 views

Registration Password

Is it best to create an application that allows a user to sign up with username and email at the beginning and password once you click the generated email sent to you or should the password entering ...
1
vote
1answer
334 views

How to crack SHA512 hexdigest passwords with John the Ripper?

I've been playing with John The Ripper (JtR) to try to crack/audit a salted password that was hashed with SHA-512, with 20 interactions according to the source (for the curious, this is a Rails app, ...
21
votes
3answers
2k 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. ...
29
votes
8answers
1k 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 ...
0
votes
1answer
45 views

How does an attacker authenticate to a service using just the hash of the user (after performing a pth attack)

Let's say the attacker got the username and the password's hash. How can he use it when authenticating to some service in its domain with NTLM , for example? How can he send the request as the ...
1
vote
0answers
31 views

Does whosthere.exe of pth toolkit have to run with administrative rights?

To see the users that are connected to the machine and they're pass hashes with Whosthere.exe, do I have to run it as an administrator?
0
votes
1answer
39 views

How does LM hash deal with passwords that are between 8 and 13 chars

If its 14 then it splits it to 7&7, but how about 13 characters? 7&6? How does it work?
19
votes
5answers
2k 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 ...
4
votes
3answers
561 views

How often should I reset my salt?

I'm thinking of implementing a salt recycling scheme on my user credentials database. The motivation behind this decision is that even if the attacker manages to get his hands on the database and has ...
1
vote
2answers
146 views

Storing database password in application

Let's say my application connects to my database. This requires me to have the username and database in my config as follows: postgresql://scott:tiger@localhost/mydatabase I have an automated ...
2
votes
2answers
7k views

Excel 2007 Encryption Strength

With a strong password of 10+ characters, mixed case, etc... Is the encryption of a Excel 2007 document secure enough to create reasonably strong defense against a brute force attack? What encryption ...
3
votes
2answers
14k views

Remove Password Protection from XLS Document

Similar to what is listed here, http://datapigtechnologies.com/blog/index.php/hack-into-a-protected-excel-2007-or-2010-workbook/, is there a way to remove the password from an XLS (Excel 2003) ...
-1
votes
4answers
137 views

How do big companies and wealthy people secure their information? And how can I secure mine?

I've recently had some success and traffic increase with an online business I own and due to that someone has hacked my domain email and twitter accounts. My bank password is the same and I just ...
11
votes
7answers
6k views

Are services like “LastPass” less secure, as they have all my passwords protected by a single password?

If the LastPass service has all my passwords and someone gets access to my LastPass password, this person will have access to all my passwords. Isn't that bad for security?
2
votes
4answers
207 views

How does a system authenticate a user using a hash function, after it has been salted?

I don't really understand how salting works. I read the Wikipedia article, but I still don't understand how can a system authenticate a salted hash? Let's say a user chooses a password. It's randomly ...
95
votes
7answers
6k views

Why are salted hashes more secure?

I know there are many discussions on salted hashes, and I understand that the purpose is to make it impossible to build a rainbow table of all possible hashes (generally up to 7 characters). My ...
1
vote
3answers
13k views

Wordlists on Kali Linux?

I notice that in /usr/share/wordlists in Kali Linux (former Backtrack) there are some lists. Are they used to bruteforce something? Is there specific list for specific kind of attacks?
0
votes
1answer
92 views

What are common problems that reveal PHP code? [closed]

What is the best method for securing PHP scripts that contain database passwords? From what I've read, PHP can be revealed when an error occurs and is not caught. Is there any way to reveal PHP by ...
3
votes
4answers
289 views

True?: “Nearly all encrypted passwords are stored with the last character in clear text”?

[S]ome passwords are gleaned by hacking into computers where intruders can find stored passwords. Those are stored in encrypted form, but there's software that can attack the encryption. Nearly ...
3
votes
4answers
234 views

When and where do I hash a password?

Say I have a client and a server. I want the user with the client to login to the server with a username and password combination. To login, they have to enter the right password which (when hashed) ...
6
votes
5answers
708 views

Is storing plaintext passwords for email accounts any less bad? [duplicate]

I recently found out that the company I use for shared hosting stores passwords for email accounts in plaintext (they mentioned this to me incidentally, while troubleshooting another issue). They're a ...
10
votes
3answers
527 views

How can I promote good password practices in an organization that doesn't currently care about that?

I work with an organization that uses some very poor practices such as using default user accounts, default passwords (or passwords the same as user accounts), sharing password information between ...
3
votes
1answer
60 views

Webpage sent me my password in clear text can it be secure? [duplicate]

I registered for a webpage years ago and have been using it without issues, today I made some changes to my account and they sent me an email containing my username and password in clear text. I ...
0
votes
5answers
1k views

Pronounceable Password Generator

I am currently looking for a password generator which produces pronounceable passwords. I have used this random password generator a few years ago to generate a 42 characters long password and found ...
2
votes
2answers
70 views

Why use PBKDF2 over multiple iterations of a another cryptographic hash function?

People often recommend PBKDF2 over using hash functions directly, but typically they compare PBKDF2 to a single unsalted hash. What advatages are there to using PBKDF2 over multiple iterations of a ...
2
votes
5answers
214 views

Password Recovery - what if user can't complete 2nd step?

I'm thinking out my password recovery logic for an ecommerce system. Some backround: Passwords are stored using bcrypt, password recovery involves the standard reset link, which then can be used to ...
4
votes
3answers
2k views

What are the odds of brute-forcing an archive with 256-bit encryption?

I have a file (a stand-alone archive). I lost the password to it, but it has been encrypted using 256-bit encryption. The password is some 20-odd characters long (including non-alphanumeric ...
110
votes
5answers
9k views

Does Facebook store plain-text passwords?

I was about to reset my Facebook password and got this error: Your new password is too similar to your current password. Please try another password. I assumed that Facebook stores only password ...
8
votes
3answers
414 views

Should I reject obviously poor passwords?

UPDATE: My questions and concerns below boil down to: "Should I reject obviously poor passwords like 'hellomydarling' or 'password'? My guess is yes and I want to know to what extent. I'm using a ...
1
vote
3answers
140 views

What are the possible rules to identify password sharing- to prevent fraud

I am trying to build correlation/ potential red flag rules to detect if passwords are being shared or stolen... the primary driver for this is guidance from our compliance team, that much of our ...
13
votes
1answer
922 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 ...
2
votes
2answers
237 views

Is this password generator safe?

128-bit entropy is required http://nxtra.org/nxt-client/js/passphrasegenerator.js With all new browsers (Chrome, Firefox, IE 11) it uses crypto.getRandomValues which should be safe, but with IE 10 ...
3
votes
1answer
150 views

Safe ways to store passwords without hashing them

I'm working on an email client for Windows, and to send emails, my application needs to have the email address and the password of that email address. When the user gives his password, I store it ...
-2
votes
2answers
99 views

Hydra https-form-post

I have never experimented much with online password crackers. I attempted to use Hydra today on this website www.athena2.harker.org and I keep getting false positives. This is what I have done so ...
0
votes
2answers
87 views

If P=NP, what is still cryptographically secure? [duplicate]

I know, I know - "If P=NP" is a really large, high-impact assumption. But this is a hypothetical. I mean, clearly RSA (and similar methods of obfuscation) would likely become totally irrelevant - or ...
4
votes
3answers
132 views

Why is password strength often underestimated and uncertain in the context of password hashing?

An aspect of security has bugged me for a long time: Why is there positive certainty about the importance of hashing algorithms and salts, but password strength is either never mentioned at all or ...
1
vote
1answer
88 views

Passwordless login over email - security considerations

I'm proposing the use of a login system that sends a one-time login token (with high entropy) via email to the user. After using the token, the user receives another token via email and the previous ...
0
votes
2answers
58 views

Logging in after password reset email sent (but not acted on)

Should a user be allowed to request a password reset email and then log in (i.e. disregarding the reset email and using their existing password) or should the current account be locked until the ...