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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How long will brute force of salted SHA-512 hash will take, if salt is known and possible characters in password are known?
Suppose I know that the password is composed of characters [A-Za-z0-9], length is unknown, but maybe less than 8. If I have information about the salt use to perform hashing, and also hashing ...
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Salt passwords with the username?
Salts should be unique so that an attacker can't brute force multiple passwords at once. However, since usernames are unique, wouldn't it be possible to use some representation of the username as a ...
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Why SHA-256 (or any other) is too fast for passwords but "slow" for collisions to be found?
Normally, the standard answers of why passwords shouldn't be stored using a groups of hash algorithms, including SHA-256 or higher, even if salted, are "because they are 'fast' hashes", "the attacker ...
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Salt length for a single password
So I've been reading about salt, and am confused about why the length is so critical. From my understanding salt is used for protection against pre-computed attacks.
Say I have a single password ...
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How do I calculate a password space if the password only has eight alphabetic characters (not case sensitive)
I read this wiki article and saw this formula for random password's information entropy. Also the wiki article mention that the symbol count for non case sensitive is 36. Is there a way I can ...
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Fixed vs variable memory access pattern in password hashing
What are, quantitatively, the pros and cons of fixed versus variable memory access pattern in Password-Based Hashing, Entropy-Stretching Key Derivation functions, and Proof-of-Work applications?
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How many bits of entropy are leaked for every derived password from a master?
Given a master password that has a lot of entropy (similar to Bitcoin HD wallet seed words, 130 bits of entropy or more) how many bits of entropy are lost per leaked generated password?
Let's take an ...
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salt usage for hashed password storage - design consideration
This is part of my academic assignment and hence to ensure no one feels i'm asking for the answer. I've given my opinion.
Hashing is mathematical one way function that takes arbitrary length data ...
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Limiting password length to "prevent hash function splitting into multiple hashes"?
Given we are using well-known hashing functions for passwords, i.e. SHA256, SHA512, BCrypt or, PBKDF2. Our Information Assurance SMEs have advised that we truncate the input into these hashing ...
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Salt and pepper at both client and server sides?
Putting aside that it may sound paranoid.
I know that many users tend to use the same password on many sites. Then, from an ethical point of view, I should not only be concerned about security breaks ...
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How can a hash function be suitable for hashing passwords, but not for deriving encryption keys, and vice versa?
Not being a specialist in this field, I am nevertheless constantly trying to keep up with which methods are being considered secure for storing passwords and for encrypting data.
During my research ...
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Use sha3 for passwords hashing
Is use of sha3 justifiable? Is sha3 better than sha2 in (m)any aspects?
P.S. I want to use hashing for passwords in a database
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What is the probability of a SHA-512 hash containing both digits (0-9) and alphabets (a-f) all the time?
Quite curious to know if ever a SHA-512 hash will contain only digits or only alphabets. Thanks in advance.
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PBKDF2 with longer than native output length - Will hashing the result help?
I've seen it mentioned more than once that PBKDF2 should not be used to create a longer key than the native output (such as 160 bits when used with HMACSHA1). Since an attacker could test only the ...
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How much less secure is an algorithm that gives feedback that the password is one character off?
If we had a stupid login procedure (SLP for short) like in this comic; it gives feedback on login, if the submitted password is one character off.
Would a longer password be less secure? What would ...
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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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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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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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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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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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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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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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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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Mixing algorithms for password hashing good or bad?
So I've come across the following algorithm for hashing passwords
...
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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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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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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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Password derived hash to encrypt known plaintext as password check
The title sounds way too adventurous for what it actually is. I am currently building a system which features some encryption. There is already a system in place, which is built after that scheme if ...
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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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Why use argon2i or argon2d if argon2id exists?
I am currently working on a project where I want to implement Argon2. The problem is that I dont really know a lot about it. Internet research is not really helpful, because Argon2 is only 2 years old ...
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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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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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Is PBKDF2/RFC 2898 broken because SHA1 is broken?
I was attempting to re-implement the ASP.NET Identity password hash algorithm in PHP. It uses RFC 2898, which uses HMAC SHA1. SHA1 has been broken by google. Does this mean that RFC 2898 in general ...
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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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Are there any known values for common hashes known to have no preimage
In a system which requires a user to have a password, as a quick workaround I wrote random junk as the bcrypt hash so that no one will be able to login to that user.
However theoretically there ...
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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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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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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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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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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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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 ...
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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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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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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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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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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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How to configure Argon2d for commodity hardware?
You may already have heard it: KeePass v2.35 has support for a new database format (KDBX4) which allows for the use of Argon2 (more precisely: Argon2d) as the password-based key derivation function (...
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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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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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