# 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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### Fastest method of CNF equation solution verification

I am trying to find a way to mine bitcoin faster than an ASIC by using a CNF representation of sha(sha(hash)), which would be an equation containing a few hundred thousand clauses, let's call it n ...
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### Can OpenSSL sign an ED25519 certificate with ECDSA-with-SHA256?

We are trying to generate some self-signed certificates to test our cybersecurity firmware before switching to a "real" CA-signed chain of trust. The specification we are coding to mandates ...
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### NIST expression for HMAC security strength

In NIST SP800-107, NIST claims that the security strength of HMAC is MIN(security of HMAC key, $2L$). $L$ is the length of the output of the underlying hash function. Let's take HMAC-SHA256 as an ...
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### Is it possible to break SHA-256 with hash tables?

If x is the value you're hashing, $t(x)$ is the hash of that value, and $t(x+s)$ is that value with salt, then hashed. You could create a hash table where the key is $t(x+s)$, the value is $x+s$, and ...
1 vote
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### Probabilistic SHA-256 hash tending all values to 0.5

I wrote SHA-256 with arrays of integers representing the bits (e.g. [1,0,...,1]), and then I altered it to accept partial values (e.g. [0.5, 0.79, 0.0, 1]), as in each value has an x chance of being '...
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### Is it possible to perform Hash(a) + "b" -> Hash(a||b)

Assume that we have (know): Hash(A) Length of A A's character type ([0->9],[a->z]) A is a string Everything about B (original string, Length, etc.) HashMethod SHA256 Note: A's original value is ...
1 vote
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### Why is the SHA256 in libsnark so slow?

When I use the merkle proof example of libsnark, I find that it takes more time to calculate the merkle tree than to calculate the proof. As shown in the log below, it takes 0.04s to calculate a ...
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1 vote
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### TLS 1.2 client finish message

Im working on TLS1.2 on cipher suite ECDHE_ECDSA_AES_128_CBC_SHA256. Im currently at the stage of client encrypted message where I always got error on wireshark from the server saying that Fatal, ...
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### How to crack sha256 used as streamcipher with known or guessable block

Using SHA-256 as a stream cipher appears to bear cryptographic weaknesses, however, I am not quite sure how to implement them in decryption. Assume that I have an encryption function using 64-byte ...
344 views

### What does it mean if two files created by the same person shares the same SHA256 hash?

Okay so I've got an assignment for cyberlaw and this could be irrelevant to the question. But I have a situation where someone signed a a will using an advanced electronic signature, but this ...
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### Can I use half of 256 bit key as AES 256 IV?

After some google research, I have found out the IV used in AES 256 bit encryption must be a 128 bit key. My AES256 encryption is processed with key of random 256 bit key and IV generated of text ...
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### Are RSA-SHA256 signatures prone to length extension attacks?

I need to sign a message using a private key and verify the message with a public key, while making sure the message hasn’t been tampered. I know that SHA-256 itself is prone to length-extension ...
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### SHA-256 compression functions without padding

Looking at the example of the null input (512 bits), it takes as input: input (Hex): ...
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1 vote
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### SHA-256 in binary-circuit-based MPC

For a binary-circuit-based MPC, the multiparty will provide its inputs to calculate the result, which indicated the function $f(x_1, x_2, \dots,x_n)$ needs to accept $2$ or more inputs. Why do there ...
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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 ...
1 vote
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### Number of Legitimate Bitcoin Wallets from unsequenced set of 24 Words

If someone found a scrambled BIP-39 24 word sequence how hard would it be to determine the correct sequence that yields someone's wallet. Are there multiple different unique sequences of the same 24 ...
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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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1 vote
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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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### Doubt regarding converting hex to byte in SHA-256 input

Hash functions such as SHA-256 takes a binary string as input. Now given a hex string when we convert it to a normal text string the computed SHA-256 value would be the same. Herein lies my problem ...
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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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