# Questions tagged [sha-512]

SHA-512 is part of the SHA-2 family of hash functions with a 512-bit output and a 256-bit security level.

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### Approximate size of image of SHA512

Let $s: \{0,1\}^* \to \{0,1\}^{512}$ be the SHA512 hash (where $\{0,1\}^*$ is the countable set of all finite $\{0,1\}$ strings. Is it known whether $|\text{im}(s)|/2^{512} \geq 0.5$? If yes, what is ...
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### Finite fiber of SHA512

Let $\{0,1\}^*$ be the set of finite $\{0,1\}$-strings. Then SHA512 can be viewed as a map $s: \{0,1\}^*\to \{0,1\}^{512}$. The pidgeonhole principle implies that there is $y\in \{0,1\}^{512}$ such ...
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### Understanding intermediate values - SHA2 - 512

I am trying to understand SHA2 - 512 algorithm, so I am following this document which has the intermediate values for the string "abc". At t=0, the values ...
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### Step-by-step working out with example input for NIST Hash Functions like SHA-1,SHA-2, and SHA-3

I am working on doing a naive Python implementation of SHA-1,SHA-2, and SHA-3 and I need to test and debug because the hash result right now is not correct. I have found a step-by-step working out of ...
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### HMAC key generation and encoding

I've this piece of .NET code that is based on a Microsoft sample on how to generate a key and sign using HMACSH256. But I've altered the key generation a little bit and also decided to use Base64 to ...
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### PBKDF2 Rounds Implementation Question?

Currently I am working on a implementation of PBKDF2 for an embedded microcontroller. My question is that my psuedo-random function is fixed (SHA-512 HMAC) how do perform 'rounds' of encryption? I am ...
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### SHA-512 - How difficult is it to find a hash digest beginning with at least twelve zeros?

I know it's possible to find a hash value with multiple zeroes in it, I know of some BitCoin hashes with it, but how difficult is it to find/create a hash digest with 12 or more leading hex zeroes in ...
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### Known text attack on Hash function (SHA 256 or SHA512)

I was thinking the below attack scenario on hash function. Let's assume that three binary numbers A(1000 bits), B(16 bits) and C(283 bits) are concatenated together and H(A||B||C) is generated using ...
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### AES Password Based Key Derivation Iterations

I have been writing my own implementation of the Advanced Encryption Standard with cipher block chaining in python3 for the last several months, mimicking the OpenSSL command line interface. I can ...
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### Bitcoin Key Recovery Without Nonce Re-Use

There are a lot of questions in these forums regarding the recovery of private keys. But I'm here to postulate on something unique to a specific piece of research that I looked into recently. The ...
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### Could a symmetric encrypted communication with a SHA-512 hash still be manipulated?

I just got back from an exam review and there was a question I remembered that I apparently got wrong. I wonder if someone could help me with this, since it bothers me. The question was something like ...
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### Why is SHA256/SHA512 not broken for shortish passwords

I don't get why SHA-256/SHA-512 hasn't been broken, at least for shortish (10-12 character) passwords It is perfectly plausible to pre-compute a password/hash-pair table using numerous very fast ...
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### Salt length in SHA-512 version of Unix crypt command

SHA-512 crypt specs reports that SHA-512 crypt uses 128bit salt. The FreeBSD/Linux password generation code builds the salt using 16 bytes random data (128bits) and then it translates the random data ...
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### Is it secure to repeatedly rehash a digest to extend the digest length?

Upon reading through the source code of Rainbow, a post-quantum signature algorithm, I found a hashing function that, using SHA-512, produced a variable length digest. This was achieved was by ...
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### What security vulnerabilities exists when encrypting then hashing to be able to search values in database?

im trying to find a good way to allow searches against encrypted data in the database. Lets say i want to encrypt phone numbers, if its encrypted securely i cant search against phone numbers directly ...
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### SHA3-512 similar message digest

How is it possible to find a similar message-digest for SHA3-512 for the first 80 bits or so? There was a Q/A on this site where the answer stated that 80 bits that $2^{42}$ computations are required. ...
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### Are there any crypto hash implementation beyond 512 bits of output?

My question is this: Are there any crypto hash implementations beyond 512 bits of output? Could you give me the link? Thank you so much for your time. Greetings.
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### 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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### Why SHA-512/256 when we already have SHA-384?

Both of them are just SHA-512 with different IV's and truncation. What's the point of having 2 of them? (Actually we have 3 of them as SHA-512/224 is the exact same thing.)
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### Is it possible to find the key of an HMAC-SHA-512 given the input and the hash output?

Is it possible to find the key of an HMAC-SHA-512 given the input and the hash output? If so, what algorithm if any prevents this? I'm working on a simple E2E communication system between two self-...
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### Is it possible to affect the output of HMAC w/ SHA-512 by providing it with a custom message?

Consider an HMAC algorithm that uses SHA-512 with an unknown private key. Is it possible to affect its output, either partially or totally, by providing it with carefully crafted messages? For the ...
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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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### Can I find a specific SHA512 for an partially-known string?

I have a plain text string "I-like-drawwing", and this string has a SHA512 value, assume the SHA512 is "aabbcc". Then I show SHA512 "aabbcc" to my friend and say: "this is SHA512 for my string, and ...
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### SHA-512 Encipherment via CBC

I wrote a cryptographic function that encrypts a plaintext by using a series of SHA-512 hashes that are used to encrypt the data via a simple byte-to-byte XOR. In order to prevent various attacks, I ...
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### 521-bit ECC keys are the same strength as RSA 15,360-bit keys

521 bit ECC uses key sizes 7.5 times smaller than the RSA standard while offering encryption that is magnitudes more secure. An RSA 2048-bit key's secure enough for banking, but a 521-bit ECC key is ...
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I don't understand how to append the length of 128 bits exactly? First, we pad bits to make the length ($n*1024-128$) but then I need to append 128 bit of the plain text length. I find the problem to ...
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### How safe is my method

I'm building a website. I have an API which takes 2 parameters: delete_user(user_id, hash). And there is method to evaluate hash using SHA512: ...
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### What is the probability of a collision in SHA-512 when the input is 512 bits of data

Although this question is strongly related to my previous question, it's certainly not the same: Suppose the input of SHA-512 is 512 bits of data (so exactly the same size as the output). If I would ...
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### Are there parts of a SHA-512 hash that occur more often then others?

Suppose I have a 'begin' password that I can remember. I calculate it's SHA-512 hash, transform it to base-64 and check if it has a least 1 lowercase, 1 number, 1 capital, and 1 sign. If this is not ...
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### PBKDF2 with SHA-256/512 for low entropy input?

Is there any reason to use something stronger than SHA-1 with PBKDF2 if my input is fairly low entropy? I.e. if the passwords being hashed are only about 30-bits of entropy. I can't find it now, ...
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### Why might SHA-384 throughput be lower than SHA-512 throughput in hashcat and more secure?

I found a hashcat benchmark results in the internet: hashcat results: SHA-384 is 17065.4 MH/s SHA-512 is 17280.3 MH/s Why does SHA-512 take less time? SHA-512 is longer and I thought it therefore ...
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### enhanced hash password in bcrypt for nuGet library

Why do we use EnhancedHashPassword in nuGet library and chose a SHA algorithm like this? ...
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### How to compute initial buffer of SHA-512?

I'm reading Cryptography And Network Security of William Stallings. In the SHA-512 section it is said that there is a 512-bit buffer is used to hold the intermediate and final result and every 64-bit ...
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### Finding and matching SHA512 Unsalted Hash

We are given a list of possible strings, there are $32^{16}$ ($=2^{80}$) to be exact. We also have the unsalted SHA512 of the original target string. How long would it take to go through those ...
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### What is SHA-512's input space, taking into account variable message size?

The SHA-512 hash function accepts any message from a single bit to $2^{128}$ bits. Because the function takes into account the message length, I can't just represent every message as a $2^{128}$-bit ...
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### What is the proof that a hash output contains random binary numbers

I have heard quotes by many that a SHA-512 hash output is random. Does anyone know what method was used to come to this conclusion? If it is not randomized, how could that be shown?
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### 19 out of 24 words of BIP39 passphrase (brute-force last 5?)

I have managed to lose 5 words of my 24 word Ledger Nano S recovery phrase. I have words 1-19 but I am missing words 20-24. I have significant holdings on the wallet so would very much like to recover ...
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### Hash collisions in sha512 hash of secp256k1 public keys

For a sha512 hash of a secp256k1 public key, how many other public keys could generate that hash? I would assume zero since the key size is equal to the hash length (secp256k1 public keys are 64 bytes,...
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### Is there any Corelation between the SHA256 and SHA512 hash of the same data?

Is there any Corelation between the SHA256 and SHA512 hash of the same data ?
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### Which is more secure for hashing: SHA512 or BCrypt with the same salt reused over and over?

Setting aside questions of if BCrypt should even be used in this way, I was just wondering which one would be more secure hypothetically. If you want to know why I don't just use random salts as per ...
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### Can i generate a SHA512 hash if i know the SHA256 hash of some unknown data?

if the SHA256 Hash of some unknown data is known ! Can i find the SHA512 of that unknown data ?
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### Worth taking performance hit of HMAC to gain additional security?

It seems like SHA-512 truncated to 256 bits is usable as a MAC [1]. The advantage is that it's ~50% faster than HMAC-SHA-256 on 64-bit CPUs and ~50% faster than HMAC-SHA-512 on short inputs. (My use ...
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### Strength of Sha512Ctr PRNG

What is the cryptographic strength of sha512ctr when I simply concatenate a counter and 64 bytes from a cryptographic random number generator (in this case RNGCryptoServiceProvider from .net), and ...
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### Why is SHA-512 limited to an input of $2^{128}$ bits?

Both SHA-384 and SHA-512 are limited to an input size of less than $2^{128}$ bits. Considering SHA-512 has a higher output size, couldn't it include more input data?
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### Calculate new hash from old hash + appended string

If I have a hash of some string in the form: hash(UNK + "known"), Is there a way to calculate the hash of (UNK + "known" + "append"), given the hash of the original value? Specifically I'm asking ...
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### Size of A Hashed String Using SHA-512

When hashing a messages of size of n, does the SHA2 algorithm always produce the same sized hashed value? The reason I am asking is that I am building an OAuth 2.0 ...
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### How long would it take to crack a double hash if salt and final hash are public?

I have a hash of a file $H_1$ and then I add salt and rehash it: $H_2$. I make my $H_2$ and salt public and I use my $H_1$ as a password. How long would it take for this to be cracked with someone ...
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### Decrypting SHA-512

I was recently solving a CTF problem and it involved a shadow and passwd file. I got to know the username easily but I am unable to find the password since it is SHA-512 hashed. My doubt is that when ...
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