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

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14
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6answers
1k views

Is there any security risk in storing hashed variations of passwords?

For example, if hypothetically an application requirement was to tell users when their password might have failed because caps-lock was turned on, and hypothetically there was no way for the ...
25
votes
4answers
4k 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 ...
19
votes
5answers
1k views

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 ...
10
votes
2answers
927 views

How insecure is PowerShell Web Access?

Windows Server 2012 comes with a new feature that allows you to administrate the server via a PowerShell command line in any modern browser including Smartphones. This sounds cool and scary at the ...
1
vote
2answers
897 views

Password entropy match for alphanumeric but there are special characters in password

I have a problem cracking some of the fundamentals on passwords' entropies. Namely: I have read this article about a guy cracking DKIM of Google (maybe more noticing that the keys are only 512 bits) ...
-4
votes
2answers
477 views

How do I construct a rainbow table to crack a 6 character password? [closed]

Given the hash: 491c290affbf5436f0fc0584ccefb2 how do I construct a rainbow table to crack this password?
28
votes
3answers
5k views

MD5 collision attacks: are they relevant in password hashing?

DISCLAIMER: This is not an endorsement of MD5 as a password hashing function. I know about parallelization, GPUs, and dedicated password hashing functions like bcrypt and scrypt. With that out of ...
4
votes
3answers
533 views

Hashed passwords - How many variations of rainbow tables?

First off...I passed the CISSP exam. WOOOO. I had to get that out. GCIH and CEH by Sept. 11' So, while studying for the technical side of things, I see that there are rainbow tables. They are pre-...
5
votes
3answers
357 views

Decoy User Account on Windows

Is there a way to have two passwords for a Windows account? One password unlocks the decoy version of the account and the other unlocks the "real" version of the account. I would use Truecrypt's ...
26
votes
5answers
3k 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 ...
6
votes
3answers
350 views

How much added security do I really get with a longer key size?

Imagine I have a cipher which supports keys of 128, 192 or 256 bits. Suppose that there are no vulnerabilities in the cipher regardless of key length. I'm going to use it to encrypt something, and I'...
2
votes
1answer
1k views

Password authentication using DynamoDB

I'm working on a Mac app. I have users stored using DynamoDB. Authentication is needed to enforce access control on system-internal operations, such as uploading files to Amazon S3. Of course, I ...
6
votes
3answers
2k views

Bank forces me to use six character alphanumeric password

My bank (it's Westpac, one of the big ones in Australia) has some strange restrictions on passwords. They're maximum 6 characters in length and it must contain only characters A-Z and digits 0-9, and ...
26
votes
12answers
9k 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 ...
10
votes
2answers
1k views

My bank makes me enter my password using the mouse. What's up with that?

Internet banking login process for Westpac requires user to enter the password using the mouse. It's annoying, what's up with that? Is it just to try and stop keyloggers on public computers or is ...
10
votes
1answer
2k views

Reversible password storage obfuscation method for third-party login credentials

I have an internal business application, that as part of its functionality connects to a third-party app using login credentials specific to the user of my own app. These passwords are stored in a ...
2
votes
1answer
287 views

Password checking in the context of symmetric encryption

It is my understanding that block ciphers like AES don't have any built-in mechanisms to verify data integrity upon decryption, although some modes of operation might provide that. I played around ...
2
votes
1answer
191 views

Security of re-encryption with a list of pre-computed password based keys

I have a problem where an encrypted file stored on a server needs to be decrypted through a precomputed list of passwords that are used one time only - OTP applied to encryption basically. The file is ...
0
votes
1answer
201 views

Proxy Non-HTTPS logins through EC2

I've been thinking a lot about password security these days, and have been becoming more and more hesitant to use services that have login forms that are not on HTTPS. As I was researching security, ...
6
votes
5answers
796 views

Creating multiple secure and easy to remember passwords

I have recently developed a new web application which our clients log into using a username and password. As we're just rolling out this system, we'll be setting the usernames and passwords ourselves, ...
6
votes
3answers
9k views

What key does Linux use when storing user passwords?

Linux typically stores user names and password hashes in /etc/passwd or /etc/shadow. Now lets say I have an old CentOS distro and I want to attempt to recover a user's password (it's in a legal, ...
4
votes
3answers
623 views

What are the security implications of phone based keyless entry systems?

I have just been reading about Lockitron which promises to provide phone based keyless entry for the home. As great an idea as this sounds it strikes me that it could come along with some very serious ...
3
votes
2answers
1k views

Is a password easier to brute force if it contains a repeating pattern?

My question is different from this previous question: Does repeating one word to form a password result in a similar pattern in its encrypted format?. I'm specifically wondering about brute force ...
18
votes
3answers
5k views

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 ...
1
vote
2answers
635 views

Known password length, brute force character in place?

We all know that brute forcing is a very slow process and trying all unnecessary possibilities is dumb. By knowing the password length, we can skip trying possibilities of other password lengths and ...
12
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5answers
1k views

If a bank says they do not have my login and password info, is that true? [closed]

After an investigation on their part, the bank simply states that if someone accessed my accounts via internet banking, (and a simswap) I was the one who didn't secure my login and password info. I ...
1
vote
3answers
1k views

How to secure data before returning Macbook Air?

I am returning my MacBook Air to Apple and want to know the best way to ensure my data is not recoverable from the flash storage. I currently have Filevault 2 enabled, however before I enabled it I ...
1
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3answers
2k views

Preventing dictionary attacks against hashed passwords [duplicate]

Possible Duplicate: How to securely hash passwords? I have a website and on that website I use SHA-256 and salt my user's passwords. What I'm doing right now is padding each letter of the ...
1
vote
1answer
210 views

tools automating logins/hashes grabbing

Lets assume I have access to the windows machine. I want to grab raw info about logins/hashes from both system and installed apps, dump and analyze it later. I could manually dump things like SAM ...
7
votes
3answers
2k views

Is it secure to use bcrypt-generated salt in cookie to serve as token in place of a password?

I have a (hobby) web site that runs only on SSL. The site does not deal with finances, social security numbers, or anything of that level of importance. However, I'd like to secure it as much as ...
5
votes
2answers
9k views

What password-based encryption to use with standard Java 6?

Which password-based encryption method should I use in Java 6? It should be as strong as possible, but work with the default security policy file (not the export restricted one which you have to ...
15
votes
1answer
943 views

XKCD #936: under what assumptions is 1000 guesses/second over a network plausible?

In XKCD #936, a rate of 1000 password guesses/second is proposed as a "plausible attack on a weak remote web service". Under what assumptions is this rate plausible? It seems much too high to me. I ...
5
votes
1answer
1k views

Can a Bitlocker To Go user pin be brute forced?

I have a external hard disk and protected a partition on it with Bitlocker To Go. I printed the recovery code but I lost it. I can't remember the user PIN either. If I could only know the first ...
5
votes
2answers
839 views

Best practice for password-protecting a secret key

What approaches are generally accepted for generating a password-protected symmetric key? My intuition is to generate and store a random string of appropriate length as the password-protected key, ...
8
votes
3answers
4k views

bcrypt: random salt vs computed salt

I'm pretty new to the whole password hashing business, so I might be missing something obvious. I was looking at the bcrypt algorithm, in particular BCrypt.Net, and I was wondering if it wouldn't be ...
-1
votes
3answers
709 views

find password and iv of an encoded string knowing the decoded string

If I would know the clear and encoded versions of a string could I somehow find the password and.or iv that wore used to encode it? Encoding done with open_ssl aes-128-cbc.
27
votes
6answers
5k 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 ...
9
votes
1answer
3k views

Why does Microsoft limit password length? [duplicate]

Possible Duplicate: Should I have a maximum password length? According to a recent TNW article: Microsoft doesn’t like long passwords. In fact, the software giant not only won’t let you ...
12
votes
2answers
1k views

Is there any advantage of bcrypt over multiple iterations of SHA-x/MD5?

I know that a good password hashing algorithm should be slow. MD5, SHA256, etc. are fast. So I've been adding multiple iterations of SHA-256 hashing to my web apps (around 50000). Getting the hash of ...
2
votes
1answer
293 views

What authentication threat data exists?

I recently read an article that said there was not much data on which authentication threat vectors were actually being exploited in the real world. Eg what percent of password theft was by shoulder-...
0
votes
1answer
363 views

How key_derivation and key_verification functions are implemented of a 7-zip archive's encryption mechanism?

I am curious about how password recovery works for password protected files. And I want to know the exact flow of the 7-zip encryption mechanism :) !! 7-zip uses the AES-256 encryption algorithm in ...
3
votes
1answer
478 views

DPAPI offline attack by cracking windows password?

I'm thinking of using DPAPI to protect configuration file information in my program. After doing some reading on it, it looks like it uses the user's Windows password as part of the encryption process....
1
vote
3answers
577 views

Linux mcrypt security

I just installed 'mcrypt'. When I try to encrypt some file with DES using the command 'mcrypt -a des myfile', I am prompted for a passphrase with a maximum character count of 512. > mcrypt -a des ...
4
votes
4answers
2k views

Is encrypting a salt value with a password/plaintext a viable alternative to straight up hashing?

The basic problem, as far as I can tell, is that hashing's flaw is that the password is in the hash. Asymmetric encryption's flaw is that the password is encrypted and can be reversed. The posts ...
2
votes
2answers
164 views

Is there a term for a “Master + extension” style password scheme?

I personally have (and preach) a password system using a "root" password shared amongst many passwords, plus a unique password component. So for Gmail my password might be correcthorsebatterystaple + ...
11
votes
5answers
4k views

Is it worth the effort to store FTP passwords encrypted?

I have a project to build a system that needs to push files to multiple third-party FTP servers. I have asked these third parties to provide a more secure interface; all have declined. So now I have ...
3
votes
2answers
6k views

Password recovery tool over telnet or http basic auth

In my feeble attempt to secure my router, I disabled the service login and either changed the "admin" login and the password, or changed only the password for the "admin" login Normally, I would ...
7
votes
1answer
3k views

Store user passwords in NoSQL database?

I am currently coding the backend of a website and I have not come across an article where this is discussed. I want to store all my application data in MongoDB but I'd like to split out my sensitive ...
7
votes
3answers
831 views

How does KeePass master key derivation increase security?

I don't understand how KeePass key derivation increases the security of the password db at all. First I'll try to explain what I understood from the key derivation described here. I'll use some pseudo ...
5
votes
2answers
18k views

Where/How is an ODBC password stored when 'saved' in Access?

I have been working on a program that uses MS Access and ODBC to connect to an SQL server. One of the requirements is that the user need not know the password for the connection to the SQL server, so ...