Questions tagged [password-hashing]
Irreversibly converting user-selected passwords into authentication tokens that can be safely stored e.g. in a user database. Typically done with a salted password-based key derivation function (PBKDF), ideally with a memory-hard mixing stage to thwart brute-force attacks using parallel hardware.
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Who invented salt, and why is it called salt?
I'm looking for an authoritative reference about the history of salts in the context of hash functions. Why is the personalization string in a hash function called a "salt"? Who should be ...
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Generating Complex Passwords from (Non-)Memorable Phrases - Need Advice
I've been thinking about creating strong and unique passwords for my online accounts, but I also want them to be memorable. I've come across the idea of using a memorable passphrase as the basis for a ...
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When trying to break a PBKDF2 SHA512 hash, how fast is an RTX 4090 or similar GPU with the given parameters
I'm writing a paper for uni about password security, specifically about cracking passwords in the context of a password manager. I've coded a password encryption scheme which uses PBKDF2(SHA512) to ...
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Can limited password/PIN length be compensated by a computationally intensive hashing function?
Say we have a very limited password space with only a 4 digit PIN, so only 10000 PIN possibilities.
Say also that the attacker has access to the stored form of the PIN.
Can breaking the PIN be made ...
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How many bits should change in a password salt?
In https://crypto.stackexchange.com/a/27828/79037, it's indicated that one can "save space" by using something globally-unique, like an application-wide "pepper", together with ...
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Cache-hard or memory-hard password hashing algorithms?
bscrypt is a cache-hard password hashing algorithm/KDF from Steve Thomas (aka Sc00bz/TobTu), who was on the Password Hashing Competition (PHC) panel. He argues it is better than the alternative ...
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Is hashing salt possible even with the password with salt appended to the end?
Should you hash the salt on its own ? Is that possible?
for example being password with salt appended at the end hash(pass || salt) and hash(salt) in a password file?
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Is it possible to sign in to a website using two different passwords using an MD5 hash collision?
I wanna do an experiment. I wanna see if it's possible to sign in to an outdated website that still uses MD5 to store passwords (there are surprisingly still a lot) with two different passwords.
For ...
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Can using an unknown, non uniform random salt increase difficulty for password attacks?
I remember reading a previous stack exchange post (unfortunately was unable to find the link, if someone knows the link that would be great!) about a method to make password checking time for the ...
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Is sha3 a one-way funtion
If i store sensitive stuff (e.g passwords, salted passwords, Internet protacel adresss(so i know its not tamperd with), private keys(the keys are using a portion of the key on multiple disks in ...
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Store the password hashing salt on a separate server to slow down evaluation?
GPUs or dedicated hardware can calculate most things much much faster than regular computers ever could. There are password hashing algorithms such as scrypt and argon2 that make the difference ...
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Use name as the initialization vector to encrypt passwords for users
I'm using AES-256-CBC to encrypt password for a set of users, and for each user in the database we gotta generate and store the password in the database. The ...
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Is there a hash function that's more expensive for an attacker than for the server?
Say a server wants to hash a password $p$. It would use a secure hash function $H$ and a unique salt $s$ to hash the password as $H(p,s)$. If one has access to the salt, each password candidate ...
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Remembering user credentials by double-hashing
I'm developing a desktop application where the users will login with username and password, which is then verified against a database. After the initial login, the current user should be automatically ...
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How can I decode the salt of this argon2i passwordhash?
I have this password hash: $argon2i$v=19$m=128,t=2411,p=2$hmJvvpH3BZlvb2V1vLm/yf3zANU4qNpKuw5TBnGzo2I$<censored>.
I know the password, and I want to verify if ...
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Does a salted password hash reveal info about the password?
Assume a password is hashed with a secure salt, e.g. hash = sha256(password+salt). If the hash and the salt are made public, an attacker can perform an attack by ...
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How is the Unix / PostgreSQL crypt function a trapdoor function?
I am looking at this in the context of password hashing in PostgreSQL, specifically, the crypt function of the pgcrypto ...
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Hashing a random string of letters upper/lower + numbers 256 characters long with SHA256
Is hashing a pseudo-random generated string of letters upper/lower + numbers 256 characters long with SHA256 insecure, in the sense that in any reasonable amount of time you can go from hash to ...
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Custom key for key wrapping using JOSE/JWK
I am trying to figure out how to use a custom password with a JWK that uses the password for key wrapping. The JWA spec contains for example "PBES2-HS512+A256KW", which does "PBES2 with ...
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Does combining multiple PBKDF2 keys result higher iteration count when using same password but different salts?
I did some experimenting with web subtle crypto.
I derived a key using PBKDF2 with SHA-512 and 100 000 iterations and timed it.
Doing same with 200 000 rounds doubled the time as expected.
Then I did ...
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Why does SHA-256 have any to do with scrypt?
I was reading the Wikipedia page for scrypt because I wanted to learn more about it and I came across their pseudocode for the algorithm. What confused me was the following line:
I don't understand ...
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Can salt just be appended to the password before hashing?
I am currently developing the back end of a website for one my projects and needed to store passwords. I knew that I needed to store passwords with salt, and my initial approach was to just generate ...
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Using Argon2, can I improve the salt join the password Argon(password,password+salt)?
I'm creating an application where I'm going to use Argon2, I'm going to have a password, and I'm going to use as salt: email+name+date of birth, you must think that my salt is silly because name and ...
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Password Hashing based on Common Passwords
If an attacker has a database of 1,000 users' hashed passwords which are hashed with SHA-256 with a 128-bit salt and all of these users used 10,000 common passwords. How many hashes will the hacker ...
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Argon2 derive two keys from one password
This is not a duplicate, I'm asking which method is better.
I generate an encoded argon2 hash string, so it'll be stored in database to verify login passwords.
Saved encoded hash has salt of length ...
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Hashes to passwords with PBKDF2
If an attacker wants to hack the passwords of $2^{10}$ users. And all of these users generate a password from the space of $2^{50}$ passwords** and each password is hashed with PBKDF2 with $2^{10}$ ...
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How many hashes to recover a salted password? [closed]
If a password p is selected from a space of 2^64 passwords, and the server stores this as a hash, h = SHA-256(p||s) where s is a random 128-bit salt. How many maximum hashes would an attacker need to ...
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How much computation it takes to crack a PBKDF2's secret salt when the passphrase meterial has been leaked
Given the following code, extracted from a Bip39 implementation for Android by Zcash
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KEY using AES-128, If P is less than 128 bits, padded with 0 and create 128 bits, any problem if average pw length is 6
For communication between the client and the website, use password (P) as the key using AES-128. If P is less than 128 bits, it is padded with 0 to create a 128 bits key. is there any problem with ...
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Best hash for PBKDF2?
I have a my own PBKDF2 automated implementation that automatically salts the hash. The output looks like this:
...
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Is it safe to initialize a random number generator with MD5?
The MD5 algorithm is no longer considered secure for most applications of a hash algorithm. However, is it safe to initialize a PRNG via a password?
If it is not, how could it be exploited?
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Can a cryptographic hash function that outputs a c-membered subset of the n-membered set?
Is it possible that there is a cryptographic hash function that outputs a c-membered subset of the n-membered set?
In other words, can the set of the binary representation of c-membered subsets of the ...
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Is it possible to bruteforce a 200 bit hash generated with PBKDF2, in which the first 160 bit are known?
As some password manager, such as KeyPassXC allows a user to create a master password using a HMAC response from a YubiKey concatenated with a password entered by user, I was wondering something.
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What should argon2id parameters be
I plan to use it locally on mobile devices. These seems to do not offer computational power as good as on a server.
So what could be a secure argon2id parameters that run around 1s since offline apps ...
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How to prove that both people know the same dictionary word?
What would be a way to prove that both you and I know the same dictionary word? If we both hashed the word, then we could compare the hashes, but anyone who saw the hash could find the original word ...
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Will increasing timecost , memorycost , parallelism in argon2ID increase security in general?
currently I am using parameters for argon2ID in terms of timecost , memorycost , parallelism higher than what is recommended in RFC9106 https://www.rfc-editor.org/rfc/rfc9106.html for increased ...
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Argon2id creating key for cryptography, how acceptable is it to use the same salt for the same encryption operation?
Everyone knows Argon2id is a slow hashing algorithm, and that's on purpose, all is good.
When creating an Argon2id object a lot of parameters are needed to be taken into consideration ultimately ...
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Can the indistinguishability obfuscator leak the password when obfuscating the password checking function?
Suppose I have a dumb password checking function:
def dumb_checker(password):
return password == "my_secret_key_that_should_not_be_revealed"
One can ...
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How to securely XOR two passphrases in JavaScript?
Is following approach secure?
Planning on using implementation to XOR two passphrases before feeding result to Argon2.
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Is there a test that put into numbers how secure a password hashing is?
As the question puts it: is there a test that can be done or a software that can be used, that is able to provide numbers/data to prove how secure a password hashing is? Say for example that I want to ...
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User to be able to log in without stating the user's password scheme possible?
In my database, I have a PBKDF2 hash + salt for every user. My objective is for the user to be able to log in without stating the user's password (in case somebody is logging the network traffic ...
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"Oblivious" Argon2id? (or comparable KDF/KSF)?
Is it possible for a client to send a blinded password to a server, so that the server does key derivation+stretching on that blinded value, but the key can then be unblinded by the client?
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Asymmetrical scheme: insecurity concerns of saving a hash of a hash of a password
please verify or explain how to do this properly.
I'm letting a user create keys from the client through a secure server.
I ask the user for a password on the client, then send the hashed password to ...
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How to create a key for AES in a 192 bit key length from a password?
Let's say that I have a password. And it's secure. But it's a 10-character string.
So If I wanted to create an AES key for the 128-bit version of the algorithm I would just hash it using MD5. Or If I ...
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Hashing and Password Cracking
I was playing a game on cryptography where I encountered this problem:
Hashed Value of password: 24 109 76 35 22 94 83 25 106 104 73 87 56 38 56 50 10
92 58 84 44 88 24 112 125 121 125 43 122 55 106 ...
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Hashing Passwords and Hash Functions
I'm a complete noob. I was reading up on hash functions. So if a bank has its user password's run through a hash function, it'll produce a unique hash for every password right? Thus, even if hackers ...
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Public key cryptography for logins
This is a question sparked purely by curiosity, wanting to understand a little more about cryptography and authentication. Thanks in advance to anybody taking their time to answer.
Instead of salting ...
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Is this authentication protocol secure against both eavesdropping and server database disclosure?
Consider the following protocol from the book "Network Security: Private Communication in a Public World" by Kaufman et al.
Alice knows a password. Bob, a server that will authenticate ...
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How does the indexing in Argon2 work?
I am reading the original paper of Argon2 authors and I can understand the algorithm except the indexing part. Can anyone explain two things:
the indexing process and the mapping $J_{1}$, $J_{2}$ to ...
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How safe is my pseudonymization procedure?
I work for an institution where patient data is collected and I am supposed to encrypt it. At the moment I do the following steps (with R):
Randomly assigning an ...
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