Tagged Questions

-1
votes
3answers
121 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 ...
2
votes
4answers
168 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 ...
22
votes
7answers
3k 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 ...
2
votes
0answers
53 views

Knowing a valid salted hash for an unknown secret, is it possible to compute another valid hash? [migrated]

H(s,r)=d is a function that hashes the string s with a salt r, giving the result d. Hashing functions are not injective, so there isn't a reverse function H'(d,r)=s. Therefore to prove that d is a ...
0
votes
3answers
102 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 ...
17
votes
4answers
972 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 ...
1
vote
2answers
113 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 ...
2
votes
2answers
254 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 ...
0
votes
0answers
34 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
votes
1answer
117 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 ...
1
vote
1answer
191 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
118 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; ...
1
vote
2answers
461 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 = ...
17
votes
7answers
2k 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 ...
10
votes
2answers
353 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 ...
2
votes
1answer
171 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 ...
2
votes
3answers
185 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 ...
5
votes
3answers
338 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
1answer
184 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 ...
6
votes
2answers
721 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 ...
-2
votes
2answers
200 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 ...
2
votes
3answers
100 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 ...
10
votes
3answers
457 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
383 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 ...
121
votes
7answers
8k 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 ...
2
votes
1answer
180 views

PCI-DSS and salt storage

PCI-DSS states the following: 3.5 Protect any keys used to secure cardholder data against disclosure and misuse I have a service which stores a salted bcrypt hash of the user's PAN. Assuming the ...
1
vote
3answers
441 views

Recompute Rainbow table with salt?

So, as I understand it, you prepend a password with salt before you hash it so that the resulting hash can't be used with a rainbow table to find the original password, as you could if the password ...
16
votes
5answers
401 views

Hashed password storage with random salt

Ever since I've been making sites that require a user to log in with a username and password I've always kept the passwords somewhat secure by storing them in my database hashed with a salt phrase. ...
16
votes
4answers
524 views

In hashing, does it matter how random a salt is?

I recently had a comment made to me in an online discussion after I'd stated that randomness in a salt doesn't matter -- and I got the following response: Salts may not have to be "secure," but ...
4
votes
4answers
574 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 ...
25
votes
8answers
2k views

Why would salt not have prevented LinkedIn passwords from getting cracked?

In this interview posted on Krebs on Security, this question was asked and answered: BK: I’ve heard people say, you know this probably would not have happened if LinkedIn and others had salted ...
2
votes
3answers
610 views

Can the salt for PBKDF2 be a hash of the user-entered password?

I want to derive a key from a password in a client application that will be used as a master key that decrypts a data key. As far as I understand the salt should be private knowledge. Would it be ...
15
votes
4answers
1k views

Why is using salt more secure?

Storing the hash of users' passwords, e.g. in a database, is insecure since human passwords are vulnerable to dictionary attacks. Everyone suggests that this is mitigated via the use of salts, but the ...
8
votes
2answers
1k 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 ...
9
votes
3answers
773 views

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 ...
8
votes
1answer
284 views

Any risk in using the same salt for several hashes on a user?

Right now I'm storing a salt and password_hash on the users table (pretty standard stuff). The need arose to get a secure hash of another field for a user. Is there any risk in reusing the same salt ...
33
votes
7answers
2k views

“Real” Salt and “Fake” Salt

During a Q&A period at DEFCON this year, one member of the audience mentioned that we're using "fake salt" when concatenating a random value and a password before hashing. He defined "real salt" ...
9
votes
2answers
2k views

What are the most common password salting methods?

I learned that the Sun guys used the login name as salt for password hashing. Is this a common approach? What are the most common salt values?
34
votes
4answers
11k views

Password Hashing add salt + pepper or is salt enough?

Please Note: I'm aware that the proper method for secure password storage hashing is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. ...
8
votes
6answers
553 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 ...