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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Safety of password manager algorithm
I would like to ask about vulnerabilities of the following algorithm for a password manager.
It is structured as follows:
There is a master password UTF-8 10 characters long, not to be stored anywhere....
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HMAC vs PBKDF2 for combining keys
I have 2 unique random 256-bit keys, 1 is public, 1 is secret that need to be combined into 1 secret key.
In my search, I found that HMAC is more suited for this purpose and does not require an ...
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Should the salt be used for data-independent memory access in password hashing algorithms?
For password hashing, is it better to compute a pseudorandom data-independent memory access pattern using the salt, the cost parameters (memory size, iterations, and parallelism), or some other way?
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database encryption scheme salt storage
I'm thinking about a page-level encryption scheme for a database, the general structure would be something like the following:
Derive KEY from PASSWORD and SALT using libsodium's Argon2ID
Encrypt ...
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Why can’t you reverse a hash? [duplicate]
I am new to cyber security and I do know the basics of password hashing works.
However, I have not been able to find an answer online to my query- although I think that it is a stupid and somewhat ...
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Is security of Manuel Blum's Mental Hash function dependent on Security Through Obscurity for it's effectiveness?
I have been practicing using Manuel Blum's Mental Hash Function for personal use, described in the link below:
Mental Cryptography and Good Passwords
However, Rob Shearer has shown that the function ...
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What is the purpose of making salted passwords public?
So I was reading through an article about how passwords are salted and hashed through a cryptographic function here, and found out that hashed passwords, along with the plaintext salt values are ...
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Boss insists on storing SHA2(p) || SHA3(p), claiming it "doubles security"
My friend in the software industry came to me with one of his "dumb boss" war stories. This particular time, his (non-technical but eager to learn) manager came to him and told him to, in ...
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Why does Argon2 truncate BLAKE2b outputs?
The Argon2 variable-length hash function uses BLAKE2b directly if the user requests an output less than or equal to 64 bytes in length. However, if the user requests an output longer than this, each ...
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Argon2 confusion when computing J_1 and J_2
I'm implementing Argon2id from the RFC 9106 and I'm at the part where each thread computes J_1 and J_2 in order to generate indices [l] and [z].
I'm confused as to which TYPE (y = 0, 1 or 2) of Argon2 ...
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Is it secure to encrypt an authentication token using another possibly hashed authentication token?
I'm working on a web app ("main") which acts as a central access hub for several other web apps ("children"). The users are supposed to authenticate in the main app, resulting in a ...
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How is Blowfish not reversible when it contains the salt in the hash? [duplicate]
I'm learning PHP and I've come to the password hashing section of a course I'm following, but it's not explained well enough for my liking.
It seems that when using the crypt function, and using the ...
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Password Manager Architecture and Design
I'm working on a local, client-side password manager. I want to hash a master password with argon2 to store it safely in an SQLite database. This will be how a user could login and be authenticated. (...
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Can you have a public password file that is still secure?
So I’ve been reading about different ways to store passwords on servers (plain text, encrypted, hashed, hashed + salt, slow hash + salt) and I wanted to find a way where a leak of the stored passwords ...
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How weak is using AES with a 128 bit key but 64 bits of the secret key are public constants?
Respected community,
I was wondering how weak would AES-128 be, if we provide only a 64 bit key with the other remaining 64 bits either zero bits or public constants, known to the attacker.
Is it easy ...
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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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