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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31
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1answer
9k views

Why use argon2i or argon2d if argon2id exists?

So I am currently working on a GitHub project of mine and 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 ...
16
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3answers
2k views

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
630 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 '...
6
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1answer
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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 ...
0
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1answer
2k views

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 ...
0
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1answer
140 views

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 ...
6
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1answer
298 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 ...
1
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1answer
487 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 ...
1
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1answer
2k views

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 ...
7
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2answers
3k views

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 ...
5
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1answer
370 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 ...
0
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1answer
94 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 ...
3
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2answers
150 views

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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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[...
0
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1answer
153 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, ...
9
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2answers
1k views

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 ...
10
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2answers
9k 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 ...
6
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1answer
2k views

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 (...
15
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4answers
2k views

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 ...
5
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1answer
303 views

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 ...
1
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1answer
713 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 ...
1
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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 ...
1
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1answer
232 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 ...
9
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3answers
1k views

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 ...
0
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2answers
204 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
634 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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2answers
308 views

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 ...
4
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1answer
3k views

Pre-image attack on MD5 hash

I read somewhere MD5 is broken in terms of collision, but I am wondering if it is broken in terms of pre-image resistance? Given a hash of Md5, is it possible to find the original message of it? If ...
1
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1answer
1k views

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
568 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=...
13
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3answers
750 views

Is it better to maximize memory usage or number of passes with Argon2i 1.3?

I wrote a small application that uses Argon2i for deriving symmetric keys for encryption of local files and secret Curve25519 keys. Argon2i v1.3 is susceptible to TMTO attacks if the number of passes ...
5
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2answers
2k views

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 ...
24
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2answers
5k views

Does the Balloon hashing paper deprecate Argon2?

Does the recent Balloon hashing paper and the included attack on Argon2 effectively negate the result of the Password Hashing Competition? On one hand it seems that only a constant-factor improvement ...
2
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2answers
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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: ...
3
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1answer
161 views

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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2answers
2k views

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
102 views

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?
3
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1answer
165 views

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 ...
7
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1answer
319 views

Are coprocessors (Intel Phi) a threat for modern key stretching functions?

Modern key stretching functions (password-based key derivation functions, also used for password hashing) are memory-hard to mitigate parallel attacks, and as far as I know this is working well. Last ...
4
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1answer
4k views

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 ...
3
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1answer
567 views

Why do different applications of hash functions demand different properties of the hash function?

A strong cryptographic hash function in general must guarantee several properties, including: Preimage resistance, second preimage resistance and collision resistance. It turns out, however, that ...
1
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2answers
719 views

Can a hash have more than one input?

From a definition stand point, can a hashing algorithm have more than one input, ex: $H(m_1, m_2, m_3)$? If not why are algorithms like bcrypt, scrypt and pbkdf2 referred to as password hashing ...
3
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1answer
379 views

Rotating password with PBKDF2

Crypto is hard. Thank you for helping me learn. My encryption scheme currently looks like this: Salt is stored out in the open Secret is the user's password, known only to them EncKey||AuthKey = ...
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0answers
60 views

Password manager that uses a mix of long and short key derivation functions

I was reading "A Convenient Method for Securely Managing Passwords, Halderman et al., 2005". In short, the authors say to do the following: ...
2
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1answer
300 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, ...
6
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2answers
327 views

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 ...
19
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3answers
9k views

What is the recommended number of iterations for Argon2?

I've recompiled my operating system ("LionBSD" based on FreeBSD) to use Argon2i as the default password hashing algorithm in crypt/libcrypt. I'm wondering what the recommended number of iterations ...
0
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6answers
3k views

Can you use a hash as a password?

There are several methods of making a strong password, making it longer is one of them. now we also have hashing algorithms which have outputs of 512, so i wonder, would it be safe to basiclly use a ...
13
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3answers
1k views

Password entropy much lower than entropy of encryption keys. Why is this acceptable?

When talking symmetric encryption, a 56 bit key is known to be so weak. If you use it for your encryption, you are considered a goner. When talking passwords however, the standard these days is ...
5
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1answer
2k views

Do I need to use a CSPRNG when creating salts for user accounts?

I'm not sure about the need of using CSPRNG to create salts for each user account. I found “Cryptographically Secure Pseudo-Random Number Generator in Qt/C++ (Cross platform)” (at StackOverflow) with ...