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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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22 views

What can be deduced/extracted from this local hash extracted from Windows Machine?

I'm new to cryptography. I've been experimenting with getting Windows hashes to see whether it's possible to reverse engineer. The following hash is what I got from my test laptop. What can you ...
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Could a fixed RSA encryption be used instead of a salt to prevent rainbow table attacks?

It's common to use a salt before hashing a password in order to prevent an attack by rainbow tables. Would it also work to encrypt the password for instance by RSA encryption - by a permanent RSA ...
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Difference between server salt and client salt?

Basically I am trying to understand the difference between server salt and client salt. I know that the client salt is used to make encryption harder for hackers, but I can't seem to grasp the concept ...
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66 views

How long would it take to calculate the hash of a password by hand?

Suppose one had no computer (or rainbow tables), but had access a pen and paper as well as all the necessary documentation for modern (best practice, not outdated) hashing algorithms and mathematical ...
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54 views

How do I calculate Base64 conversion rate?

Basically I need to have a base64 encoded signature that has to be 96 characters long. However, I do not know what length I need to have the signature at so when I encode it, it can be that exact size....
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73 views

Choose Argon2i or Argon2id for secure password hashing on a website? [duplicate]

I make a website with authentication. I have studied a lot of answers to these questions, but I still don't understand what is better and safer to use for a website: Argon2i or Argon2id? I know which ...
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91 views

How secure is a password generator that runs SHA256 on a passphrase

I was looking into how password managers work and it seems to me that they all store the passwords (albeit encrypted). How secure would a scheme be where the password manager always generates the ...
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18 views

How do NTLMv2 hashed passwords work?

We have an application which embeds NTLMv2 password hashes into its configuration. In attempting to assess the security of this practice, I'm not finding much straightforward information about how an ...
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AES with a longer key instead of key expansion? [duplicate]

What are the disadvantages of using AES-256 with 240-byte key (which scrypt/bcrypt/argon2/pbkdf2 can easily output) instead of an expanded 256-bit key? The only disadvantage I can think of is "no ...
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722 views

Does having a hash of a password jeopardize the security of plaintext that was encrypted with that password?

A malicious actor wants to decrypt ciphertext that was encrypted with a password. He also possesses the hash (bcrypt/PBKDF2) of that password. Does he have any significant practical advantage in ...
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202 views

Relation between Zoom id,password and join URL [closed]

We all are using zoom application for joining/hosting meetings in this corona virus period. As we create a meeting, a new id, password and a url is generated. Some real examples follow- Id: ...
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39 views

Hashing-Simple Hash and Merkle tree [closed]

Does the output hash of simple hash and Merkle hash are same for same data>>??
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Short term for “Purposely-slowed hash”

When Argon2, Balloon, scrypt, bcrypt¹, PBKDF2… are used for a password, we can call them password hash (for password storage) or password-based key derivation function (for use in encryption). But ...
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64 views

how many iterations of SHA3 (keccak256) hashing would be required to provide reasonable protection for the following data structure?

((A , B , C) , (D , E , F, G, H)) Where: A is 0x0-0xF, (1 of 16) B is 0x00-0xFF (1 of 256) C is an 8 digit integer D is a one of a list of one hundred words padded to 12 characters E is a one ...
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Argon2id benchmarks

Recently I've decided to publish a simple app that I am using for maintaining and storing sensible encrypted data on the cloud. https://www.microsoft.com/store/apps/9NSGBQSJ2HD6 The hashing is done ...
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Do we still need Multi Level Password Hash if Brute Force is not a matter

I am developing a web application where user can SignUp and all that kind of stuff. I was doing some research about Hashing and Storing passwords in Database and came across this article. In this ...
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1answer
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Does pepper *require* an HMAC?

Assume you are already given a properly-salted, password hash $X$ from some slow PBKDF (e.g., like Argon2id). Now, you want to apply some large (~256-bit) secret "pepper" $S$ to it before storing it ...
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Length extension attack in the middle help!

is it possible to insert the command that you want to execute in the middle of the md5 hash token already known?
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153 views

How to bruteforce password from HMAC-SHA256 hash (if you have the key)?

Short of creating one's own script / program, is there an existing, readily available way of iterating through a list of potential passwords to find which one corresponds to a hash (HMAC-SHA256), ...
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2answers
215 views

How to pad a 448 bit message for SHA256?

I recently implemented a very simple SHA256 hashing program in C++, since the SHA256 hash function's block size is 512 bits or 64 bytes, and messages less than that size have to be padded as per the ...
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Signal Key Stretching Regarding Their Blog Post

I just read this blog post (Signal - Technology Preview for secure value recovery) by Signal and something is not quite clear to me. In section "Stretching beyond a KDF" they generate a ...
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5answers
164 views

How passwords are fed to key derivation functions?

Suppose I want to encrypt data, send it over the network, and decrypt it on the receiver side. I know the elegant way to do this is by using a symmetric key to encrypt the data and an asymmetric key ...
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1answer
73 views

Choosing between hash functions instead of providing a salt for a password hash

I am working on some programs that require the users to store their passwords in my databases. However, due to the fact that I am not sure whether salt should be stored in databases due to my ...
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1answer
87 views

How slow is the hash used for Mac FileVault encryption?

Certain password strength estimators (for instance, zxcvbn) give estimates that vary with the speed of the hash and the assumed resources of the attacker. I am curious what hash is used by the MacOS ...
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3answers
253 views

How to securely store and validate a 4-digit PIN used on a mobile device?

I want to be able to securely (1) create and (2) validate a PIN, typed by a user primarily in a mobile app. There is no 'typical' password, although there is another 2nd factor. The starting point ...
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47 views

Two party protocol using only hash function

I have been told by my professor to compare two passwords as we do it in Yao's two-party protocol but without using any crypto functions. We are only allowed to use a hash function. The passwords are ...
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2answers
84 views

Cracking hashes: With vs without knowing the salts

Let's assume the following situation: The attacker has extracted 1000 password hashes from a website (vuln.com) along with all their usernames and hashing ...
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80 views

Password hash salt

I'm asking this question to have a professional opinion about this, and to check if my assumptions are correct. The question derives from few comments I exchanged on SO: Problem with login I can login ...
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2answers
118 views

Losing entropy after re-hashing a hash

Suppose you have a string AAA that was hashed with SHA1 to produce 606ec6e9bd8a8ff2ad14e5fade3f264471e82251. If I rehash ...
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2answers
87 views

Risks hashing salt + 5 - 8 number pin with PBKDF2

I have been tasked with putting a simple sign in experience in place where the user types in their ID and a 5 to 8 numeric value as the password or PIN as it is called here. I am using ASP .NET Core ...
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1answer
39 views

Is there a PAKE algorithm that is fully resistant to a server data leak?

I'm looking to build an authorization system with a completely "public" server which involves two assumptions: The server's data is public The server is incorruptible and uncrackable i.e. nobody can ...
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1answer
269 views

Argon2 or scrypt instead of PBKDF2 with AES

Is using scrypt or argon2 a better key stretching technique with AES compared to PBKDF2 or bcrypt with regards to a quantum computer brute force attack. The brute force attack I'm referring to is ...
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Why are good passwords required if we use good hashing algorithms?

Again and again are we adviced to make good passwords: At least 12 chars, numbers, signs, upper and lowercase. But why is that really needed? I can see the need, if the system uses a hashing ...
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Clarification of NIST Digital Identify Guidelines and “Pepper” in Password Hashing

For password hashing the NIST Digital Identity Guidelines state In addition, verifiers SHOULD perform an additional iteration of a key derivation function using a salt value that is secret and ...
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Is there a point in storing hash or plaintext in the last column of Rainbow Tables

As I read up on rainbow tables, I found that most sources suggest storing a plaintext - the result of Rk(hk) - in the last column, while others just store the hash hk, basically stopping one step ...
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exfiltrating salts with timing attacks?

It seems to me that it's theoretically possible to exfiltrate a salt against a hashing algorithm that isn't constant time using specially crafted inputs. Are there any examples of this being done in ...
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111 views

How would quantum computers affect password based encryption?

At first glance: Assuming that the output of the password hashing function is large enough, quantum computers should have no effect on password encryption as on symmetric cryptography in general. Is ...
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1answer
104 views

Password to password mapping

DISCLAIMER: I understand the question might be a bit amateurish due to my limited knowledge of cryptography but, please, bear with me for a minute. QUESTION: Suppose a user Alice generates a pass ...
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236 views

Does character encoding change entropy?

This is a question I've been wondering for a while. Technically these two strings have the same entropy I believe: ...
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1answer
90 views

Add a pepper to a hash: as a string or a buffer, and should I calculate a hash of a peppered plain text?

I'm using a bcryptjs to generate a computationally slow hash function for storing passwords: ...
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1answer
70 views

Understanding Encryption length calculation and rounds

I am trying to learn about password encryption by creating a simple password hashing algorithm, although many online articles did warn "Do not create your own algorithm". I discovered that most of ...
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757 views

Can you find the salt if you have the original password in plaintext and the hashed version?

Suppose that I have a password in plaintext. I also have the hashed version of the password. Say it uses MD5. Is it possible to find out what the salt is given the above information? I'm guessing not?
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How secure are public hashed passwords (with a salt)?

I'm working on a blockchain-based distributed application which stores Client information. I'm thinking of alternate ways to authenticate ...
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4answers
912 views

How is PBKDF2 so much better than normal Hashing or even using HMAC

I do not know how the Key Length extension attack works. So if we leave that aside for once, and say just about usual brute-force attack on the hash, I don't really know how is PBKDF2 so much better ...
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What is used as a KEY and MESSAGE when using HMAC within a PBKDF2? [duplicate]

I was studying WPA2 and it's security when I came across this problem. I know that WPA2 uses PBKDF2 to generate a Pairwise Master Key. It does something like this; ...
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1k views

When to use Argon2i vs Argon2d vs Argon2id?

I've read the manual, and multiple articles / StackExchange posts about this topic, but still can't decide which implementation of Argon2 is best for my use case. I want to securely encrypt passwords ...
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64 views

Authenticating without sending password to the server, and store data encrypted with password derived key on server

I am trying to think of a scheme that would allow a user to authenticate to a server, whithout sending the password to the server, and to also derive a symetric key on the client (that also never gets ...
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895 views

Password Hashing Security Using Scrypt & Argon2

I am developing an app where the following cryptographic system will be in place: Elliptic Curve key exchange (curve: secp521r1) Double Scrypt the shared secret with different salts Pass this result ...
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1answer
41 views

Keyed Hashing and verification

Is there any standard algorithm where I can create a hash H(x,k) where x being the data and k being the private key. And verify on other end with H(x,l) where l being the public key? How it can be ...
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1answer
69 views

Choice of delta-neighbors in Balloon Hash algorithm

Reference Document: https://eprint.iacr.org/2016/027.pdf According to appendix D section 4 definition 27 each vertex in V has predecessors sampled independently and uniformly at random from the ...