Questions tagged [sha-256]
SHA-256 is part of the SHA-2 family of hash functions with a 256-bit output and a 128-bit security level.
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Challenging $O(2^{n/2})$ for hash collisions using quantum computers
In "Finding Hash Collisions with Quantum Computers by Using Differential Trails with Smaller Probability than Birthday Bound" the authors Akinori Hosoyamada and Yu Sasaki state that it may ...
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Uniqueness and Schnorr signatures
I am trying to analyse a "uniqueness" game around Schnorr signatures. The game is described in $\textbf{B.}$ and I try to provide in $\textbf{1.}$ and $\textbf{2.}$ some incomplete answers ...
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Depth of $\operatorname{SHA-256}$ implementation by fan-in $2$ and fan-out $1$ Boolean circuits?
A fan-in $2$ and fan-out $1$ Boolean circuit is a circuit consisting of $\operatorname{AND}$, $\operatorname{OR}$ and $\operatorname{NOT}$ gates where number of inputs to $\operatorname{AND}$ and $\...
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Is there a reason behind the number of bit rotations used in SHA-256?
SHA-256 uses the following bitwise functions during the hash algorithm:
$$\begin{align*}
\Sigma_0^{\{256\}}(x)&=\operatorname{ROTR}^{ 2}(x)\oplus\operatorname{ROTR}^{13}(x)\oplus\operatorname{...
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Is this a secure (and correct) sign-then-encrypt technique for transferring messages?
After reading some information on the way iMessage works I have been working on writing some code to try my hand at securely transferring messages in a similar manner and I wanted to confirm that the ...
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Is it safer to use timestamp in REST authentication?
I am working on a personal project to build a REST authentication system which authenticate clients via three parameters:
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Is the sha256 x86 extension close to optimal in silicon? (as it relates to a VDF)
I came across the Solana network utilizing sha256 as a "proof of history". They are using it as a pseudo-VDF (verifiable delay function). The reason it's pseudo is because verification is ...
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Is it better to use PBKDF2 with SHA-512 and 1e6 iterations or SHA-256 and 6e6 iterations?
I'm implementing encryption in my browser extension that will allow users to encrypt their data and then share them with others. And since shared links can be leaked, I want to protect the data as ...
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Is my TypeScript scrypt implementation using Web Crypto API safe and correct? (Open Source)
I want to use TweetNaCl.js for encrypting user data that is stored in LocalStorage. Therefore, I want to prompt the user to provide a PIN/password that shall be ...
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What is more secure, HMAC with SHA-1, or with SHA-256 and take a substring?
I'm going to guess the latter, but just wanted to ask here.
I want to have a relatively short signature, and my goal is to take a substring of the resulting hash.
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Creating a basic SHA256 hasher in Circom
I want to create a SHA256 hasher in Circom so I can validate that a person knows the pre-image of a SHA256 hash without revealing the pre-image. This is my current code but it doesn't work:
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SHA-256 Hash Crack
Suppose, If a SHA-2 hash does get broken completely with hardly any power, where would it get reported and is there currently a bounty on it?
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Matching accounts across multiple data leaks via their hashed passwords
I've heard about several instances where OSINT researchers were able to match user accounts from multiple data leaks purely based on their hashed passwords, assuming accounts had the same password on ...
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vec_sel in SHA-1
I can't find what is vec_sel() in this optimization from Wikipedia:
Instead of the formulation from the original FIPS PUB 180-1 shown, the following equivalent ...
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How quickly can we compute SHA256?
Disclaimer.
I have asked a similar question on Electronics StackExchange: they advised me to try here.
The question
I am in the process of developing a simple protocol whose security relies on the ...
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TLS 1.3 clarification needed on hello_hash and subsequent hashes
I am exploring TLS, mainly from the server side at the moment. I am creating a server that will authenticate a client using TLS 1.3 and eventually I will be creating a client authenticating to a ...
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Hash coordinates (back-end) without the client (front-end) knowing the coordinates, but to be able to guess them
So I have a set of coordinates and I will hash these with a random salt with SHA256.
Coordinate range is 0,100.
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Does fixing partial bits of a SHA256 hash increase the probability of finding a preimage using the meet-in-the-middle attack?
Let’s say I want to find a partial rather than full preimage using the meet-in-the-middle attack. For example, my goal is to find a preimage so that the first 76-bit output of the hash are all ...
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Idea behind internal SHA-2 functions
In the SHA-2 family, specifically SHA-256, there are functions called Sigma0 and Sigma1, which look like this:
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Can I prove that hash of modified preimage is valid
Assume that hash(X) == Y
Alice knows both X and Y
Bob only knows Y
Alice generates a random nonce N and shares it with Bob.
Alice calculates H = hash(X⊕N) and shares H with Bob.
Can Alice prove to ...
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KCV scheme that encrypts a hash over key and IV
Is there anything wrong with this key-check value scheme?
This question is a follow-up to an earlier question of mine. In summary, I want to devise a key-check value scheme that will enable my ...
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Handling key invalidation
I'm writing an Android app which will need to store some data for the user as a byte array of unknown length. The data must be encrypted. I have gone down the path of the hardware-backed keystore and ...
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Hash function notations and their corresponding existing cryptographic hash algorithm
I am implementing Role-based access control by referencing the paper Enforcing Role-Based Access Control for Secure Data Storage in the Cloud. In page 6, they have mentioned to choose hash functions $...
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Keys and key-stretching when authenticating requests?
I'm making a REST application and still a bit confused about this issue. basically, to authenticate incoming requests, I give out userId, issued timestamp, expiry timestamp (normally 3 months after ...
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Designing an AES-based protocol for controlling and acessing ioT boards via RF
I'm designing an open ioT protocol to be used on ioT boards based on Texas Instruments RF-based MCUs. These MCUs have an AES module to easily encrypt and decrypt AES content, so that's why I choose a ...
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HMAC-SHA256 key length against key recovery attack
I have trouble finding information on the security strength of HMAC-SHA256 against key recovery attacks with respect to the key size.
To fit a certain application I must use a 128-bits key with a HMAC-...
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Explanation of KeePass 2 database key calculation?
I am currently taking a course in university where we are working with a KeePass 2 database file. I am still very new to everything which has to do with encryption.
First I am going to provide the ...
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Generate SHA256 fingerprint from RSA public key (string only)
I have the public key, the string itself (not a file), and I am trying to figure out the SHA256 fingerprint, as in the image attached. The default key generated by PuttyGen is SSH-2 RSA with a SHA256 ...
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What is the minimum length of shortened HMAC to be considered safe?
Is it safe to truncate HMAC? What is the minimum length of a truncated HMAC so that HMAC is still considered to be safe to use? Are there any standards on when it comes to shortening HMAC?
In my case, ...
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Bug Bounty for a reversed Hash
this is just a general question, Is there is a bug bounty from the NSA or anyone else for reversing a SHA HASH, specifically SHA-256?
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Protect PII in-transit via hash comparison
I'm being asked to provide a solution for my internal customer. All network communication is internal and no applications nor their servers are accessible via the internet.
REQUESTOR application will ...
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Generating certificate using ECDSA_P256 algorithm but with sha256RSA signature
If you have a look at a certificate encrypting google.com it advertises a 256-bit ECC key with ECDSA_P256 parameter. The signature algorithm is sha256RSA. I've been ...
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How does one construct a SNARK circuit for proving the knowledge of a SHA256 pre-image?
Usually one explains how the R1CS/QAPs and SNARKs work using examples of circuits with multiplication and addition nodes, and constructing polynomials from that is relatively straightforward. SHA-2 ...
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Is 64-bit SHA-256 IV-based MAC for fixed-length messages reasonably secure?
I want to use truncate8(SHA256-nopad(IV=secret, message)) as a 64-bit MAC, where message is guaranteed to be exactly one hash ...
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TLS1.3 transcript hash
From RFC8446:
For concreteness, the transcript hash is always taken from the
following sequence of handshake messages, starting at the first
ClientHello and including only those messages that were ...
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SHA3_512 as dynamic SBOX generator
I'm creating a substitution-permutation cipher (for learning purposes only of course) and I'd like to implement dynamic SBOXs. The cipher will have a block size of 128, and 32 rounds. These SBOXs will ...
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Is this a good implementation of digital signature with timestamp?
Is this a good practice ?.
How good or bad is this compared to appending a timestamp to the actual data and hashing it as represented below.
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Can I and How Decrypt this Online
Although I had a security course in school a long time ago, I am effectively new to cryptography.
I have an encrypted text, the encryption key of 44 characters, the encryption method, (Fernet, which ...
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Probability of collision when we use a particular part of sha 256 hashed value
So I was supposed to use hash some co-ordinates and I was supposed to use k 3-wise independent hash functions in order for the mathematical explanations behind that algorithm to be hold. But after ...
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Is Joux's multicollision attack applicable for truncated SHA256?
Joux presents an elegant way to generate k-way multi-collisions with about as much effort as generating a single collision: https://www.iacr.org/archive/crypto2004/31520306/multicollisions.pdf
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Should I update my fedora encrypted system?
I have installed my Fedora Workstation version 23 using native disk encryption. Since it, I am upgrading it using dnf system-upgrade plugin. Today, I have fedora 32. Some time ago, I’ve discovered ...
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Combining Hashes - NTLM and SHA
i have been recently learning about different types of hashing and the encryption/decryption methods of such hashes. Im currently trying to find the preimage of this hash i have been given as a ...
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Is it possible to reverse the final rounds of SHA-256
I've seen a lot of preimage and collision attacks on SHA-256 that target the first few rounds. So far, the best attacks break preimage resistance for the first 52 rounds out of 64 rounds.
However, I'...
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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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Why initialize values and array SHA256 with specific buffer?
Why initialize values and array SHA256 with specific buffer?
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Rotate values in predefined manner
I want to create a Server S1, that publish a different value every 10 minutes on the internet. The value looks something like f7826da6-4fa2-4e98-8024-bc5b71e0893e.
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Explaining the reason of radically more accuracy while using different set of hash functions instead of same set of hash functions on some operations
So I am looking for an explanation of an experiment.
In this experiment, I took a set of k hash functions. Say the total number of data points I am working on is d. Call an algorithm A which used that ...
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How to pad in the SHA256 Algorithm (an example using Bitcoin Header)?
For any bitcoin block we combine various Header fields to create a string which is an input to a 2 pass SHA algorithm. The resultant hash must match with the Hash in the Block header for the Block to ...
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Does a pseudo-random number have the same security as its SHA digest message?
Is a random number generated by a CSRNG equivalently secure as the SHA hash of that number? I know that RNGs generate numbers that look random, and aren't necessarily random. For example, in a range ...
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