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

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Clarification on how rainbow tables work

If you goto : http://www.hanewin.net/encrypt/aes/aes-test.htm for "Key in Hex" enter 00000000000000000000000000000056 for "Plaintext in Hex" enter 00000000000000000000000000000000 and click on "...
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5answers
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How valuable is secrecy of an algorithm?

On the surface, the inadvisability of security through obscurity is directly at odds with the concept of shared secrets (i.e. "passwords"). Which is to say: if secrecy around passwords is valuable, ...
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4answers
4k views

iOS app - hash user password in-app or on-server?

I'm working on an iOS app that will also have a web component. When a user creates an account, their password will be salted and hashed. I already have the hashing algorithm working on the web-side. ...
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6answers
5k views

Is there a table that compares hashing algorithms by speed, relatively (machine independent)

As far as I understood*, one of the major criteria when choosing a password / salt hashing algorithm is it's speed. To prevent brute force attacks, a slower algorithm is better (and also makes it more ...
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6answers
3k 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 ...
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7answers
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Are password reset links that don't expire a security risk?

I am currently working on a password reset flow. We have decided to go with a password reset link being emailed to the user's registered email and allowing them to follow that and input a new ...
3
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2answers
872 views

How should you store a password that needs to be retrieved as plaintext? [duplicate]

Possible Duplicate: How should passwords be stored if they must be recoverable? I have created an API for a site that doesn't provide any form of API. For the API to do anything with the ...
2
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1answer
107 views

What's the best way to enumerate log/sign in attempts?

For sign in via a website, what is the best way to count the number of attempts that is: least vulnerable to tampering reliable quick The system would: use HTTPS throughout the sign on phase (at ...
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3answers
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Key stretching a hash

If I implement a function which hashes the first half of my password with MD5 and the second half with SHA-2 and MD5, is there a security issue when I put these two hashes together to create a 64 ...
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9answers
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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.
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11answers
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Is it safe to use a weak password as long as I have two-factor authentication?

I'm careful to use strong passwords (according to How Big is Your Haystack, my passwords would take a massive cracking array 1.5 million centuries to crack), I don't reuse passwords across sites, and ...
3
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1answer
223 views

SRP: Can the client authenticate using only the stored hash?

Based on the description of SRP, it seems that it would be possible for a client application to cache the hashed password x and reuse it for subsequent authentifications. The actual password p doesn't ...
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3answers
272 views

Does a 'reset password' website facility give away too much information?

If a website has a reset password facility (which will e-mail the account holder a reset link), does this facility reveal too much information by allowing someone to probe who holds an account by ...
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2answers
791 views

Is dual control password is a feasible way to secure against unauthorized login?

I see that some organizations practice dual control password especially when it comes to critical system logins, etc. Is it feasible to implement such policy considering certain trade off such as ...
2
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3answers
335 views

Passwords In Securing Network Devices

I don't do anything with corporate IT and networking, but I know enough to handle and get networks going. Anyway, something I ran into in my travels when it comes to the occasions of working on ...
56
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12answers
4k views

How do you log in from an unsecured computer?

Suppose that you are on a cybercafe, at a friend's home or at your work office, and you need to log in on a site, but you feel that the the computer can not be trusted (e.g. your friend isn't tech-...
3
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1answer
383 views

Is there a better way to take advantage of current 'approved', 'proven', and memory/cpu-expensive algorithms while using salts and peppers?

I've read about the concepts presented in these two questions: Pre-hash password before applying bcrypt to avoid restricting password length Would it make sense to use Bcrypt and PBKDF2 together? I ...
4
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1answer
120 views

Is there such thing as a smart phone with auto-forget password feature?

Storing passwords to external services (e.g. corporate email servers) on smart phones is very insecure, since phones are more easily stolen. Has any vendor implemented a feature to only cache a ...
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2answers
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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 ...
0
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1answer
115 views

Credentials using AWS IAM

I have a server, which should provide temporary credentials to the client. The credentials will be transmitted using HTTPS. The client should be able to upload S3 files, as well as download them. The ...
3
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3answers
204 views

What are some ways to steal a password/PIN using this system?

http://cups.cs.cmu.edu/soups/2007/posters/p147_lim.pdf Essentially uses an on-screen keypad that does not show the complete keypad numbers at a time. The image is refreshed at the rate of the ...
19
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4answers
988 views

Should I be concerned when a “Forgot Password?” tool sends my password in plaintext?

Some sites I have been a member of in the past don't go through the normal "Forgot Password?" process. Instead of e-mailing me a unique password reset link or something of the like, I have received ...
5
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3answers
688 views

Unmasking passwords during sign up, is it a good idea?

I just read this article about unmasking passwords at sign up for usability reasons. On the surface it seems reasonable to me, but I'm wondering what additional security concerns that might generate, ...
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3answers
685 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 2.6.2),...
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2answers
894 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) ...
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3answers
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I don't see how “-salt” in the openssl command line tool enhances security at all

I do this to encrypt a single file: openssl aes-256-cbc -a -salt -in file.txt -out file.enc and then type in some regular plaintext password. I do not understand how -salt enhances the security of ...
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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?
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3answers
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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 ...
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3answers
356 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 ...
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4answers
2k views

My credit union is reducing its maximum password length to 10 characters

I just received an email from my credit union saying they are redesigning their online banking service and that I will need to change my password by October 22 to conform to the new limit of 10 ...
6
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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
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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 ...
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2answers
926 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 ...
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3answers
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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 ...
10
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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 ...
2
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1answer
286 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 ...
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7answers
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My company policy states I must put all passwords in a password safe shared with management. Is this secure?

As the title says, my company has a policy that all passwords to e.g. our workstations and server logins must be stored in an online safe. I won't say which one but there are some out there you can ...
10
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1answer
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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
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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 ...
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1answer
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Password length limits in history of operating systems and popular web sites

I heard that many years ago for example passwords on linux systems were limited to 8 characters. Or rather, you could type in more than 8 characters, but only the first 8 characters mattered. ...
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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 ...
0
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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, ...
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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, ...
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11answers
4k views

How to easily remember lots of different passwords?

I know that you shouldn’t use the same password on every site. But, when you log into several dozen sites, keeping track of all the passwords can be pretty hard. What system do you recommend that won’...
3
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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 ...
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2answers
634 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 ...
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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 ...
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3answers
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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 ...
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1answer
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How to apply a pepper correctly to bcrypt?

Update: There is a better way to add a server side key, than using it as a pepper. With a pepper an attacker must gain additional privileges on the server to get the key. The same advantage we get by ...
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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 ...