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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6
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1answer
303 views

What is the role played by cache misses in memory-hard password hashing?

I experiment with argon2 and build a web application. In browser, I use one threaded hashing with not too much memory. I want to protect my short length input data from parallel brute-force attack. I ...
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1answer
196 views

Does this PBKDF2-SHA1 payload hint at a cryptographic security issue?

Blockchain first 16 encrypted bytes, IV, and iter_count – all encoded in Base64: Yms6xqrzCfFsQadVZ5gQonMtnQAAAAAAAAAAAAAAAAAAAAAQJwAA69tYNg== Does it looks like “...
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Why do two Argon hashes with the same password differ?

Can someone explain to me what the ArgonHashString function in libsodium returns (i'm using the .net port). For example i called it twice with the same string: ...
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Comparing different hashes to confirm they came from the same string

Is there any safe hashing algorithm that returns a different hash each time (like bcrypt) but has the possibility to compare 2 different hashes and determine that they were hashed from the same ...
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Password hash that can be upgraded without plaintext password

Most password hashes have a cost parameter that indicates how long the algorithm should take. Is there an algorithm where you can increase that cost for a particular hash, without access to the ...
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Cryptocurrency serving as hash breaking?

There are many people mining for Bitcoin right this second.[Citation needed] Bitcoin's proof-of-work mining system is based on a hash function (SHA-256, I believe), and there are ASICs built ...
2
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1answer
119 views

Pepper and key derivation/stretching

I understand the pepper concept of adding but not storing a secret and iterating through the set of possible secret values for verifying. But is pepper also useful when it comes already to the use of ...
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2answers
159 views

hashing and message input size

If a hash function like Whirlpool or Sha512 would take a byte array of 1 MB in size filled with the output of a Secure RNG as its input message, would this be considered a strong input message, a ...
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Prevent communication with a node assuming full transparency

I have an IoT device that I have set up to communicate with AES-256-GCM encryption. The working version has the encryption key stored in plaintext in a file on the device (this is going to be improved)...
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4answers
956 views

Rehashing PBKDF2 hashes - do iterations stack?

Let's suppose I have a bunch of PBKDF2 hashes in a database. For the sake of keeping this simple, let's say I've used 10 iterations. A few years later I decide to upgrade to 20 iterations. I want to ...
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1answer
186 views

Security trade-off when using low number of rounds with SHA256

I have a web application that stores hashed password reset tokens in a database table. The tokens are randomly generated 256-bit values. I'm currently using Python's passlib sha256_crypt function to ...
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Best password hashing strategy with Argon2 in a web app

What are reasonable parameters for Argon2 to hash passwords in a web application? On the one hand we need good performance, fast responses and DDoS resistance, but on the other hand we need protection ...
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Why did Argon2 win the PHC?

I've been reading up on Argon2 (and, to a lesser extent, other recent password hashers). I'm trying to understand why it won the competition versus the other finalists, like Catena, Lyra2, Makwa or ...
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1answer
476 views

scrypt and argon2: binary safe?

for bcrypt it's probably common knowledge that it isnt binary safe because it uses null termination, which means that when bcrypt is used you need to make sure that no one does these (e.g. by hashing ...
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2answers
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Mixing algorithms for password hashing good or bad?

So I've come across the following algorithm for hashing passwords ...
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1answer
226 views

Generating secure hash using iPhone Secure Enclave

I need to turn a password plus salt into a 256 bit hash. The hash is used as a key to encrypt / decrypt a database on an iPhone, so it need never be generated outside the phone. It also need not be ...
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435 views

What math makes it safe to offer a stolen-password check service?

The database provider HIBP has 4 billion stolen passwords, and wishes to offer an API for websites to use during new-user signup (and password change) operations, so they can refuse to allow users to ...
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1answer
924 views

Can pbkdf2 be used with a fixed salt to give a deterministic slow hash?

I need a password hashing function that is deterministic. Correlation attacks are not a concern. The same password must produce the same hash. I just want to protect the password against dictionary ...
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1answer
635 views

Finding hash algorithm given password and hash

Is it possible to find the hash algorithm used for a password given that you have the clear-text password and its hash? The algorithm in question hashes the string 'password' to '...
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2answers
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How to crack hash: MD5(MD5(SHA1(SHA1(MD5($pass)))))

I have a hash that I know is MD5(MD5(SHA1(SHA1(MD5($pass))))), which I want to decrypt. However I have yet to find any tools which can decrypt this. Right now my best idea is to write a python script ...
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1answer
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extract password hashed in scrypt using hash and salt [closed]

I have the hashed password and its salt. It is encrypted using SCRYPT by firebase. How can I extract the plain text password from these two? Or alternatively, how can I re-encrypt or convert them ...
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1answer
502 views

Question about hashing passwords with PBKDF2

I am new here and new to encrypting and securing passwords, so please forgive me if this question is not posted to the right location or if my question is bad. I have been working on a web app in ...
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1answer
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What is the minimum recommended number of rounds for Argon2?

I'm hashing passwords with argon2 using Python's passlib library and am wondering how many rounds I should use to future proof security. The default uses 2 rounds but I'm wondering if it'd be sensible ...
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2answers
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Is there a perpetual 2-factor-authentication scheme that allows temporary password generation?

Recall that current forms of two-factor authentication (2FA) rely on: Something you know, i.e. your password Something you have, i.e. your one-time password (OTP) generator on a trusted device The ...
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Whats the deal with argon2?

So I recently read an article about the Argon2 hash function. Now some Questions: I heard that it was developed in 2015 so why is it not implemented yet? If so where is it implemented? ( I think I ...
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1answer
380 views

Upgrade password hash in an existing system: Pbkdf2( salt , OldSha1Hash )

Background [Updated] Consider a situation where a website was created over a decade ago and user account password storage was done by storing SHA1(password) into ...
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1answer
95 views

Using simple hashing function to expand already secure key

Assume I only have only three algorithms available at my disposable: PBKDF2, SHA512, and HMAC-SHA256. (This means I do not have algorithms like HMAC-Expand available.) Assume I also have a ...
5
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1answer
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How does blockmix in scrypt work? What is the meaning of the H function in scrypt?

I am trying to understand how scrypt works. I am referring to the Algorithm section of scrypt's Wikipedia page. There I find ...
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1answer
4k views

Determine hashing algorithm [closed]

I have a plaintext and a hash output, two hash outputs to be precise. One is HEX encoded, and I have no idea on the other one. plaintext=halflife hash=1e4dfacf77efceb3076bb551932e6e40 hash2=PN[...
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1answer
154 views

Lyra2 sponge construction and random numbers?

I have a Lyra2 project and I still have some problems understanding its principle. I really found a problem when I read about sponge contruction. I found out that it's composed of 3 steps: absorbing, ...
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1answer
720 views

storing salt in app

I want to create a key for my realm database wich work with AES-256 and for encryption wants a byte[64] key. I read this good question about create a key from 4 ...
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2answers
10k views

Storing Parameters In Argon2 Hash As Potential Security Issue?

I'm really trying to make sure that I follow best practices when it comes to password storage, and after some looking around for a good algorithm, I found that Argon2 was the "next big thing". I've ...
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4answers
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How is the quality of a password calculated and what does it mean?

While using Keepass and using it to generate random passwords, I always have noticed the "quality" section but truthfully have never known what it actually means. So my questions are; How much ...
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1answer
89 views

Encrypting user-specific hash?

When a user registers, a random personal salt is generated. Then hashing is done like so: hash(hash(USERNAME . PEPPER . PASSWORD) . PERSONALSALT) Then the ...
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1answer
235 views

securing the keystore

When generating a public-private key pair you have the option to secure the keystore with a password. where is that password stored, is it a hashed version that is stored and if that is so which ...
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2answers
206 views

What is the probability of the first half of a hash output being identical to the first half of another hash output?

Let's say for example that I encrypt a password with some hash function and receive a 256-bit hash value in return. What are the chances that the first 128-bits (half) of this value are identical to ...
0
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1answer
652 views

Hash algorithm for converting n-bit number into another n-bit number

So I'm new to this area of Stack Exchange, and to cryptography in general, but I just wanted to ask this question here to see if I could get any advice. I don't understand a lot of the technical ...
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Very simple, very memory-hard (?) password-based key derivation

I know the problem of memory-hard password-based key derivation functions is better left to the likes of scrypt, argon2, etc... But validated implementations of those algorithims are not always ...
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1answer
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Storing passphrase and encrypted private key

I have to protect a key pair with a passphrase and to store these information someway in a table. I read that I can protect the key pair (specifically, the private one) using a digest of the ...
2
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1answer
574 views

anything obviously wrong with my custom password hash scheme?

i sha2-256 hash the password, then i base64 encode the hash (per RFC 2045) , resulting in a 44 bytes string looking like LPJNul+wow4m6DsqxbninhsWHlwfp0JecwQzYpOLmCQ=...
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1answer
301 views

Salting Hash stored on RFID tag?

In my application, I am trying to prevent counterfeit widgets from being used on our gadgets; think HP ink-cartridges. I will be doing such with UHF RFID tags embedded in the widgets. Unfortunately, ...
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2answers
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Is the SHA1 hash of MD5 hash of a password secure?

Cryptography is not my area, so pardon me if the question is annoying. Some time ago, I implemented an Internet site, which database had a users table. To keep the password in its user table field, I ...
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Are there any high level memory-hard PBKDF constructions?

The PBKDF2 construction from PKCS #5 v2 has the convenient feature that it can be implemented using only standard interchangeable cryptographic primitives. Specifically, it only requires the ...
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1answer
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Does AugPake not require key stretching?

I was reading the AugPAKE rfc and noticed that there is no mention of key stretching anywhere. The protocol does mention use of a hash function, and the hash function that is provided as an example is ...
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1answer
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RAR brute force cracking speed

I have been playing around with cRARk and was astonished by the low speed. On a 2015 high-end GPU (GeForce 980 ti), it took roughly 4h 50min to test all passwords composed of an 8-character prefix and ...
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2answers
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what is the procedure to make my own hash encryption? [closed]

I am posting this question here for the procedures(If any) of making my own password hashing technique. Because bad encryption makes the severe damages as far I learned
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2answers
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What if I make the hashing with an own function ? Does it make unhackable?

I am thinking to create own hashing Instead of creating encryption(weak). That hash function has some number of cryptic parameters to go before it stores in db? Does it become unhackable if I do so?
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1answer
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Security implications of repeated hashing

I have an hash function hash() I can easily compute the hash of the string "hello" like this: out = hash("hello"); What are ...
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0answers
493 views

Password hashing in embedded systems

Are there good options for password hashing in embedded systems? These systems often cannot afford slow hash functions. I can think of a few approaches: Store the (hashed) passwords in a HSM that ...
17
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3answers
5k views

Should you change salt when changing password?

Assume a password storage scheme using a computationally-expensive hash algorithm and a CSPRNG salt. User ID, salt, and hash value are stored in a table; if the table is compromised, all three ...