A salt is a random addition to a password to make the hashed password less susceptible to a lookup table attack

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3
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685 views

Reverse-engineering password salts

Lets set out a scenario, a database has been dumped and all the passwords are hashed. You notice that some users seemed to have signed up twice and have the same hash. You run these hashes through ...
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1answer
285 views

Challenge, Authentication and session key

I programmed an application on Linux using C, I added an authentication and cryptography layer that's going like this : 1 -client sends connection request. -server send a random challenge to client. ...
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2answers
213 views

How can I generate a unique SALT for multiple apps sharing one user database?

Let's say that I have one Database, and several separate web applications that share the database. If hashes are to be unique and generated on the server-side, how can I ensure that I am generating a ...
12
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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 ...
0
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1answer
600 views

How long would it take to brute force the AES encryption?

I'm trying to write a secure code that can keep my site users passwords as safe as possible. Now I'm fairly new to encryption and would like some professional opinions and suggestions. As well as a ...
3
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3answers
202 views

Proper storage/use of salted passwords?

If a salt is not stored along with the hashed password in the database, is it possible that the password is salted? I ask because in a system I am working on there is only a password column, but when ...
7
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2answers
414 views

Salt placement prior to one-way hash

In one-way hashing its common to prepend or append the salt to the secret and then hash it: (salt + secret) or (secret + salt). I was thinking of this metaphor as salt falling on a plate of food. It ...
0
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3answers
258 views

Need references about why public access to a password hash and salt is poor practice

What are some published industry standards about why revealing the password hash and salt are poor or bad practices from a security perspective? I am dealing with a vulnerability where anyone can ...
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3answers
3k views

Generating an unguesable token for confirmation e-mails

I'm generating a token to be used when clicking on the link in a verification e-mail. I plan on using uniqid() but the output will be predictable allowing an attacker to bypass the confirmation ...
5
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3answers
749 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 ...
4
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4answers
436 views

User password as key instead of hashing it

I was reading here on Hashes and Salts and I thought about another method to do user authentication. I need your thoughts on this as I might be overlooking something. Scenario: For web application ...
2
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1answer
1k views

How to save the random salt to the database

As I understand it, salting and hashing passwords is the way to go. I also understand that to authenticate a salted and hashed password, the random salt needs to be saved. Does this mean that if I use ...
8
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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 = ...
5
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5answers
913 views

Is it a good idea to use an input by the user as SALT?

I have read many Q&As here on IT Security about password hashing and salting. I am building a simple registration form for our community website which will be used by our members to create their ...
3
votes
3answers
816 views

How can salted, hashed password storage be combined with a plaintext, nonce and hash based authentication?

My understanding is as follows: To securely store a password (e.g. in a database), you use a hashing algorithm designed for this purpose (designed to be slow, e.g. bcrypt), and you use a unique salt ...
-1
votes
1answer
232 views

After salting my passwords, are they protected against dictionary attacks? [duplicate]

I use sha1() to hash my users passwords, but recently a friend told me that if someone get the hash then they could use dictionary attack and he recommended using salts. I implemented a random salt ...
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3answers
205 views

Salting in encryption (rather than hashing)

I am aware of the benefits of adding a salt to values that are hashed using a one-way function. Is adding a salt to a value that is being encrypted (using symmetric encryption) considered to be good ...
3
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4answers
370 views

When salting and hashing passwords, any advantage to including password length?

In this answer, Gilles says (emphasis mine): There's no need to hide the salt from the attacker: it needs to be unique (and not derived from the password) but it doesn't need to be more secret ...
30
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7answers
8k views

Is salting a hash really as secure as common knowledge implies?

(I did search on this topic, but I found no complete question/answer that addressed it, or even good portions of questions that might be relevant.) I'm implementing a salt function for user passwords ...
0
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3answers
435 views

Why one time passwords using nested hash chain are not used?

I am wondering, why web sites do not use one-time passwords generated by hash chain. By that I mean that a client chooses a secret and after being salted, he applies some secure hash function F() on ...
20
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5answers
2k views

When hashing passwords, is it ok to use the hashed password as the salt?

I don't like this idea. But I can not come up with a technical argument against it. Can somebody explain it to me? The basic idea is: $passwd = 'foo'; $salt = hash($passwd); $finalHash = hash($passwd ...
6
votes
2answers
421 views

How less secure is an encryption if we know something about the original data?

I have a number of files encrypted with a key derived from a password. In line with standard practice, I use a random salt and password and do many PBKDF2 iterations to obtain an encryption key and ...
2
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2answers
391 views

How high is the entropy of this salt-generating code? (No code-reading actually necessary)

What is the best method? Assumption: I have a function that generates a number of medium-high entropy bytes Step1: I generate 3 of these medium-high entropy bytes. Step2: I hash these bytes using a ...
3
votes
4answers
531 views

Is it safe to have the salt equal to IV?

If I'm using AES-256 CBC to encrypt, getting the 32 byte key using multiple iterations of the PBKDF2 function with a 16 byte salt, is it safe for me to let IV be equal to the salt? (Edit: The salt is ...
3
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2answers
2k views

Why doesn't Microsoft implement salt on users passwords in Windows?

Pretty straightforward - So we use rainbow tables to get passwords of users out of hashes. So why won't Microsoft implement salt on the passwords in Windows to be hash(password+salt)? Won't this ...
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0answers
39 views

Database hash for password field [duplicate]

I'm using a mysql database and am looking for a cryptographic hash method for a password with salt added to it. What would be the best hash method for this problem?
0
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1answer
445 views

Determine hashing algorthim only with known input and output

Given the input: test A system generates the following output hash: 0x001F41B6A0534D3B851D69EFE6237F550100000010D5F4FC65E64BCFDBF2590212E4411C44942C6C734C00ACFE13B958DCAB3614 I do not know ...
2
votes
1answer
1k views

I've heard that salt is not meant to be secret, but what if I made it secret? [duplicate]

Possible Duplicate: Password Hashing add salt + pepper or is salt enough? How to store salt? Ok I have been studying a lot about password hashing lately. And I have a few questions. So I ...
2
votes
1answer
197 views

Can a salted hash be an effective MAC?

An HMAC is basically a "keyed hash". Only the correct message and the correct key will produce a particular hash digest efficiently. Conceptually speaking, the same can be said for a salted hash; ...
4
votes
2answers
3k views

should i use urandom or openssl_random_pseudo_bytes?

I am developing a site in php 5.4 and i was wondering which is better to use to gen a random salt for password security? $salt = sha1(openssl_random_pseudo_bytes(23)); or $seed = ''; $a = ...
8
votes
3answers
783 views

How to authenticate a salted password?

If only the password hash is stored and the user inputs the original password, how does the program know that it is correct? I guess it could check all the possible salts but if there are 32bit salts ...
21
votes
7answers
4k views

Why don't people hash and salt usernames before storing them

Everyone knows that if they have a system that requires a password to log in, they should be storing a hashed & salted copy of the required password, rather than the password in plaintext. What I ...
14
votes
2answers
483 views

Password Salts and Randomness

Alright, so I understand that users are the kind of beasts who like to use one password and make it short and easy to remember (like "doggies"). If I understand correctly, that's one reason we use ...
4
votes
4answers
2k 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. ...
3
votes
1answer
289 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 ...
7
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3answers
3k views

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 ...
2
votes
3answers
323 views

Password Security: Encrypting salt [duplicate]

Possible Duplicate: Password Hashing add salt + pepper or is salt enough? I'm new to security and trying to understand why encrypting or hiding a salt is not considered useful. I've read ...
1
vote
1answer
758 views

cracking MD5 with salt using JTR

In a legal, learning context at school, we have to understand security in Linux in the /ect/shadow file and the anaconda-ks.cfg. These two files contains often different kind of hash and the password ...
7
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3answers
790 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
3answers
2k 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 ...
11
votes
1answer
7k views

Where is the salt on the OpenSSL AES encryption?

I'm interested in knowing how and where OpenSSL inserts the generated salt on an AES encrypted data. Why? Im encrypting data in Java classes and need to guarantee that I can use OpenSSL to decrypt ...
4
votes
3answers
2k views

optimal way to salt password?

A good way to salt password? I have read a few answers related to salting password. But I started to get confused. I came across few functions people used to generate salt like: mcrypt_create_iv() ...
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votes
1answer
473 views

Global salt vs salt-per-password [duplicate]

Possible Duplicate: Password Hashing add salt + pepper or is salt enough? Any risk in using the same salt for several hashes on a user? It's known that all password hashes need to be ...
12
votes
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 ...
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2answers
332 views

How to secure passwords when site is opensource [duplicate]

Possible Duplicate: How to securely hash passwords? How can I store passwords to have them secure? Right now the site use md5 md5, I was thinking about sha1+salt but if the source code for ...
31
votes
7answers
10k views

How can crackers reconstruct 200k salted password hashes so fast?

I'm researching for a small talk about websecurity and I found one article about the formspring hack, which made me curious. They claim to have used SHA-256 + salt We were able to immediately fix ...
2
votes
3answers
115 views

Clarification on an email about a security breach

I got the following email from a forum I was subscribed to: It is our duty to inform you that there has been a security breach on the server that Doom10 was being hosted on. It doesn't seem like ...
11
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3answers
734 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 ...
15
votes
7answers
669 views

To salt, or not to salt? [duplicate]

Possible Duplicate: Why is using salt more secure? Why would salt not have prevented LinkedIn passwords from getting cracked? Recently I decided that I wanted to learn more about web ...
186
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6answers
23k views

How to store salt?

Nowadays, if we expect to store user password securely, we need at least do the following thing $pwd=hash(hash($password) + salt) then store $pwd in your system instead of the real password. I have ...