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

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Can a dictionary attack crack a Diceware passphrase?

Everyone knows the words used in Diceware passwords (all 6^5 = 7776 words are published) -- they're all common words. Everyone seems to know that we're not supposed to use dictionary words for ...
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6answers
3k views

Managing website passwords for small team

I'm part of a small group of people who manage a website and the server it runs on. We have many accounts with third-party websites or services that multiple people on the team need to access. What is ...
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3answers
2k views

Should security question answers be case-sensitive?

Question In the case of security questions being used to reset an account password, what is considered best practice for handling case-sensitivity on the security question answers? Scenario An ...
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2answers
2k views

Tamper-proof BIOS password & settings storage with Trusted Platform Module?

In the olden days, one could trivially bypass BIOS passwords on most PCs by removing the BIOS battery and clearing the CMOS. My question is: On modern PCs equipped with a Trusted Platform Module ...
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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 ...
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3answers
2k views

Known characters in passwords?

I generate passwords for everything that requires security using the following method: ksoviero@ksoviero-Latitude-E7440:~$ head -c 16 /dev/urandom | base64 gorv/cp+lSiwiEfKck2dVg== 256^16 ...
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5answers
2k views

Can sites which check your password as you type pose a security risk?

Some sites that I use check my password as I type it into the login (not registration) form. So, for example, to begin with I might have: Username: sapi ✓ Password: passw × and by the time I've ...
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5answers
8k views

Is saving passwords in Chrome as safe as using LastPass if you leave it signed in?

Justin Schuh defended Google's reasoning in the wake of this post detailing the "discovery" (sic) that passwords saved in the Chrome password manager can be viewed in plaintext. Let me just directly ...
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3answers
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Cracking MS-CACHE v2 hashes using GPU

As most people here will know, Windows caches domain/AD credentials in a format known as MS-Cache v2. Obviously, these would be excellent passwords to gain during a penetration test when local access ...
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2answers
175 views

Would suggesting a random passphrase during sign-up hurt overall security?

I've been looking for ways to improve security and security awareness for both internal and external clients and I happened upon the idea of generating a one-time, random "password suggestion" on the ...
13
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2answers
357 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 ...
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6answers
7k views

Is PBKDF2-based System.Cryptology.RFC2898DeriveBytes() “better” for Unicode Password hashing than traditional methods?

When is it appropriate to use RFC2898DeriveBytes versus a typical hash? Update I now understand that a KDF is typically used to create a symmetric key for possible use in encrypting a stream. I ...
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2answers
550 views

How Does A Random Salt Work? [duplicate]

I don't understand how using a random salt for hashing passwords can work. Perhaps random salt refers to something other than hashing passwords? Here is my thought process: The salt is used to add ...
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6answers
2k views

Do salts have to be random, or just unique and unknown?

First of all, my motive is to avoid storing the salt in the database as plain text. As far as this question is concerned, the salt is not stored in the database. After discussion in comments and in ...
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3answers
3k views

Password in file .php

My connection.php file stores the credentials to connect to the database. <?php $objConnect = mysql_connect("localhost","username","password"); mysql_select_db("selectDB", $objConnect); ...
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4answers
1k views

Is it “standard” to SMS passwords?

When I get credentials for a new machine, my company will often send the login id in email, then SMS (or sometimes Skype msg) the password. This is obviously in order to separate the login and ...
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6answers
2k views

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 ...
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3answers
8k views

Possible to use both private key and password authentication for ssh login?

It seems that they are mutually exclusive, as disabling one gives me the other, and vice versa. Two-factor auth for my ssh servers sounds really nice, so is there any way to accomplish this?
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4answers
1k views

MS-SQL Password Storage

What would be your recommendation for replacement of an MD5 hash approach to password storage within an MS-SQL database be?
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2answers
6k views

Facebook API : App Secret - possible misuse

I've recently find out that by simple quick look into compiled code of one of our applications, you can get both App ID (API Key) and App Secret for Facebook API I suppose that we should really keep ...
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2answers
3k views

How big salt should 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 ...
12
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3answers
630 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
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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 ...
12
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2answers
544 views

Zip file with two password

I used this command to password protect a zip file on Linux : zip -P 9000 hash.zip hash.py and it creates the zip file just fine, then I wrote a program to test every possible password on it from 1 ...
12
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3answers
417 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 ...
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6answers
25k views

Is howsecureismypassword.net safe to use?

Is it safe to enter my real passwords to test them? I mean, are the entered passwords being recorded/transmitted to someone else?
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3answers
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How can I prevent someone from accessing a Windows XP system via boot disk?

Apparently a computer system protected by a a login password, e.g. Windows XP, can be easily hacked by someone with physical access to it using methods like this one: ...
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4answers
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Handling passwords in a web application

I am trying to learn how a secure web application is developed. Particularly, I am unsure of how passwords are sent from the client to the server. For a typical user/password login form. If the client ...
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3answers
708 views

Does the salt need to be unique or not predictable?

I always thought that salts is simply used to prevent rainbow tables to be used. Other have suggest they should be unique on a per account basis. Currently i have been using a config file to use as ...
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3answers
715 views

Do users of non-latin character languages suffer from spyware and trojans?

Do Chinese, Japanese, other languages that can't be represented in ASCII get their passwords stolen? I figure there can't be some sort of bruteforce attack software for them, right? Their characters ...
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3answers
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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 ...
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2answers
1k views

How secure is asking for specific characters of passwords instead of the entire thing?

In some password-authenticated sites, you are asked to enter a random selection of specific characters from your password rather than the whole word/phrase. For example, it might say 'Enter the 1st, ...
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7answers
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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?
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5answers
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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 ...
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4answers
2k views

How secure is NOPASSWD in passwordless sudo mode?

On all our boxes we have ssh access via keys. All keys are password protected. At this moment the sudo mode is not passwordless. Because the number of VMs are growing in our setup, we investigate the ...
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5answers
700 views

Is there any good reason not to salt/hash passwords you store?

Two organisations I frequently deal with (including my bank) ask me my password to authenticate myself with them... well... they ask for "random" characters from my password. As I understand it, this ...
11
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1answer
527 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 ...
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5answers
523 views

Security of carrying passwords on person

While in college I decided to have a randomly generated 16 character password. I used parts of that password in various sites. However, one of the sites was compromised so I had to change my password. ...
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3answers
778 views

How much information about the reason for an unsuccessful login should a web application give?

After an unsuccessful login attempt, should I inform the user about its reason? Or more generally, how much information about the reason for an unsuccessful login attempt should a web application ...
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3answers
10k views

Is a password protected PDF file safe for bank statement attachments?

My bank emails my monthly statement to me in a password protected PDF attachment. Is this a secure method of transmitting something as sensitive as bank statement?
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2answers
3k views

With PBKDF2, what is an optimal Hash size in bytes? What about the size of the salt?

When creating a hash with PBKDF2, it allows the developer to choose the size of the hash. Is longer always better? Also, what about the size of the random salt? Should that be the same size as the ...
11
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7answers
734 views

Aren't password managers still incredibly risky?

I understand the utility in having one application remember a bunch of long, randomized passwords, but all you'd need is one well-placed phishing scam or a keylogger and they get all the keys to the ...
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4answers
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How can I make sure password hashing is secure on computers while not being prohibitively slow on mobile devices?

I'm new to cryptography and its implementations. I'm designing an Android app where an user enters a password to retrieve some encrypted data. After some research on possible solutions I ended up with ...
11
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1answer
394 views

“Please Enter Nth Character” without HSM

This question has been asked a few times, but always in the format "How does examplewebsite.com implement their 'please enter xth yth and zth characters of your password' function?" And the ...
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3answers
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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 ...
11
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5answers
465 views

What is the best way to hand out passwords to a widely spread diverse employee base?

I have a problem I need to solve - specifically, how to hand out passwords to people in a variety of locations, and with a wide variety of access. I've thought of some options, but there are ...
10
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4answers
3k views

Authenticating without a database

I've been inspired by a question over on Code Review, which boils down to: What is the proper way to authenticate a user without a database? Would it be the exact same process if you stored ...
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9answers
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Why do we authenticate by prompting a user to enter both username and password? Does prompting the password only suffice?

I don't know why do we authenticate by prompting the user to enter both username and password. In my mental model, prompting password only suffices. The reason is as follows: Assume there are x ...
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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? ...
10
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5answers
763 views

Altering passwords before storing

Assume that I'm using bcrypt with a unique salt (or some other best practice) to hash user passwords before storing them in my database. Is there any security advantage to be gained by ...