Questions tagged [sha-3]
SHA-3, also known as Keccak, is a cryptographic hash function standardized by NIST as a new alternative to the SHA-2 hash function family.
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Security implication of concatenating two hashes using different algorithms
Background
Hashing files is an expensive thing for CPU. I am tasked to write a secure digital signature scheme. For that, I decided to check the integrity of files using Hash/Digest.
To be more secure,...
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Padding of SHA-3
SHA-3 uses Padding, so the original message has a certain length.
In the case of SHA-3-512 each block has the size of 576, so any message must be padded, such that it is a multiple of the blocksize ...
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Layman understanding of SHAKE128 XOF
Need some help. I am not versed in hashing and just started programming with PHP and currently need to hash some strings but required it to be unique. Found that OpenSSL can hash with SHAKE128 but ...
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Safest alternative for hashing credit card numbers to use the hash as fingerprint?
Same question asked here in 2014 but since a lot has changed since then, I would like to get feedback from experts on the latest best practices.
The problem
Our requirement is to provide the ...
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1answer
52 views
How does re-hashing affects security strength?
I am currently saving hashed passwords for my website. Passwords are salted and then hashed using SHA3-512. I understand the security level of SHA3-512, as it is for all Keccak algorithms, is half the ...
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SHA-3 for Integrity
We used to use CRCs to check the integrity of files. For safety analysis we could associate a probability for detecting a corrupted bit in a large file. Now we are using an RSA Signed SHA-3 hash for ...
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1answer
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Recommended Shake256 digest size for KMAC based HKDF
On the wiki page for HKDF, in the Python Implementation, there is a hash_length variable for the ...
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127 views
SHA3 the Left & Right Encode Functions
In this paper (Section 2.3.1, Pg.5), I came across the left_encode and right_encode functions, and I have some questions about ...
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133 views
Split hash for 2 keys
These are the steps:
Hash ECDH shared secret with SHA3-512
Concatenate odd bytes and rehash with SHA3-512 for AES-256 key
Concatenate even bytes and rehash with SHA3-512 for KMAC key
Is this key ...
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59 views
Hashing high entropy key into AES format
If I have a high entropy key (ECDHE shared secret), what type of hash should I use to format this into an AES-256 key? Is Sha256 or Sha3_256 sufficient to maintain entropy or do I need to use a KDF (...
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1answer
126 views
SHA3-512 troubleshooting - is there a worked example for hashing the “zero-length string”?
(I wondered if this question should be asked on StackOverflow instead because it's a programming related issue, but it's bound to the intricacies of SHA3, which I figured was a better fit for Crypto....
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How to interpret a specific mathematical notation in “FIPS 202” (SHA-3 / Keccak)
tl;dr What does "d <= |Z|" mean in the context of bit array manipulations?
As a learning exercise I'm working on an implementation of SHA-3. I am not a cryptography specialist in any way but I ...
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SHA3-255, one bit less
I need a SHA3-255 or 511. What if I simply truncate a standard SHA3-256 or 512? Apart from the doubled probability of hash collision, are there any other things I should be aware of? I could also ...
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Is there an input length range for SHAKE128 hash function?
For SHAKE128 hash function in SHA3VS document, I find this paragraph:
Therefore, for testing SHAKE128, (168*2)+1) = 337 unpredictable messages will be
generated with lengths from 0 to 337 336 ...
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Why isn’t SHA-3 in wider use?
SHA-3 was released by NIST just over 4 years ago this week. In my experience it does not seem to be as widely used as I might have expected. I see SHA-2 and even SHA-1 more often. What are your ...
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234 views
Where do the constants for SHA-1/2/3 come from?
My request is:
I need to know the source of constants (shift constants, IV, or S-Box) for the following algorithms:
SHA-1
SHA-2 (all sizes)
SHA-3
Examples:
BLOWFISH uses the hexadecimal ...
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2answers
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SHAKE-128/256 or SHA3-256/512
Would it be better to use SHAKE-128/256 or SHA3-256/512? In what situation should I chose one over the other?
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How padding works on SHA-3? [duplicate]
I'm studying SHA-3 and I dont understand quite a bit how the padding 10*1 works. Can someone explain me step by step how is it work? Also I know that on SHA3-512 r is 576. On the sponge construction ...
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What is the difference between SHA-3 and SHA-256?
I am new about cryptography,
I learned that SHA-3 (Secure Hash Algorithm 3) is the latest member of the Secure Hash Algorithm family of standards, released by NIST....
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1answer
524 views
SHA-3 Step by step?
Can somebody explain me or give me a link of a step by step SHA-3 explanation it has been really hard for me to undesrtand it. I would love to see an explanation since it's input untill the digest is ...
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1answer
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What does the minimal number of round of “nr” use Keccak to avoid “collision attack”?
What does the minimal number of round of "nr" use Keccak to avoid collision attack?
$$nr = 12+2L$$
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1answer
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OAEP security with variable length hash function
I'm implementing a hobby cryptosystem for fun and to increase my knowledge on the subject, and I was wondering if the OAEP construct was still sufficient as an all-or-nothing-transform if variable ...
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Integrity check of a binary firmware file with hash function
I need to provide a mechanism that it is possible to verify the integrity of a firmware image flashed on an embedded system. The procedure should be, that if someone has doubt on the firmware’s ...
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What do the security definitions of SHA-3 mean, quantitatively?
In the SHA-3 standard (page 31) the security of SHA-3 is defined quantitatively, for example, they are saying SHA3-256 provides 256 bits of preimage resistance. How is this number of bits to be ...
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1answer
187 views
What is the minimum message length to obtain the full potential of a hash?
Suppose I want to commit to a uniformly picked nonce of fixed length $n$ bits without revealing the nonce, so I use a secure hash function $H$ mapping messages to digests of length $d$ bits. Suppose $...
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Computational Complexity of SHA-3 (SHAKE128)
Please, I got the question "what is the computational complexity of SHA-3 (SHAKE128)"?
What does that mean and how can I calculate that??
*I am using SHA-3 (SHAKE128) in my mechanism to hash fix ...
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Intuition for SHA3 sponge construction
I would like to get some intuition on the security of the sponge construction. I'm referring to this diagram and notation.
Let's consider the case where we have don't apply $f$ in the squeezing ...
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1answer
248 views
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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What does Keccak being “efficiently invertible” mean?
Reading through Wikipedia, I saw this:
It has been shown that the Merkle–Damgård construction, as used by SHA-2, is collapsing and, by consequence, quantum collision-resistant, but for the sponge ...
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1answer
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Why is SHA-3 robust against Length-Extension Attacks?
If a length extension attack can occur because of $H(\text{K}\mathbin\|\text{Message})$, what changed in SHA-3 from SHA-2 that prevents this from occurring?
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1answer
273 views
rotation offsets for KECCAK-$f$[800]
So let's say you're trying to do SHA3-224.
If you're on a 64-bit machine you'd presumably use KECCAK-$f$[1600]. In-so-far as I understand it'd have the following parameters:
Rate: 448 (2*224)
...
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1answer
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why was padding changed when keccak became sha3?
In the original Keccak you would pad by adding a 1 bit proceeded by a predetermined amount of 0 bits and then another 1 bit.
When Keccak was standardized to sha3 the padding was changed. It was then (...
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mapping a 256 bit random number to a 3 bit number
I am making a 2 player dice game that runs for n rounds. To create random dice roles im using a concept a understood from randao.
each user generates n sha3 hashes recursively of a random seed : e.g. ...
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Benchmark (hash rate) for SHA-3 (SHAKE128)
To estimate the time for brute-force attack we need to compute keyspace size divided by hash rate, where the hash rate (hash/second) varies depending on the computer's capabilities.
The website https:...
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1answer
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Benchmark for SHA-3 (Shake128) [duplicate]
I am trying to find the average of hash rate (benchmark) for SHA-3(Shake128) for a normal and supercomputer in order to estimate the brute-force attack which I can get if from ( keyspace / hash rate )....
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How secure is using a hash function as Key Derivation Function?
I am developing a personal project and I have the following need:
given a randomly generated seed (with enough entropy) I need to generate a number $x$ of Ed25519 key pairs.
These key pairs are not ...
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Hash Function SHA-3 [duplicate]
I would like to discuss the minimum input of hash function to consider strong (e.g Shack128 (SHA-3)). I have a mechanism based on SHA-3, but the input is just 40-bit, some friends told me 40-bit input ...
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SHA3 hardware implementation [closed]
I am studying SHA3 in order to create a hardware implementation, preferably in verilog. I have downloaded VHDL reference implementation from https://keccak.team/hardware.html.
The code is great, and ...
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1answer
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0.75 confidence in bit prediction through $\chi^{-1}$
When checking the S-Box implementation of $\chi$ in Keccak I wanted to see if there were any fixed bits in the forward direction of $\chi$ that could be leverage to reveal truncated state bits.
I ...
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1answer
412 views
Will the ECDSA with SHA-3 implementation be quantum-proof?
I know, that ECDSA could be broken by quantum computers, but since there is post-quantum hash function SHA-3, does not this make the digital signature resistant to them?
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Why is SHA3 prefixed with SHA despite the fact that it is structurally different from SHA2 and SHA1?
Why is SHA-3 prefixed with “SHA” despite the fact that it is structurally different from SHA-2 and SHA-1?
SHA-0, 1 & 2 and MD5 is based on Merkle–Damgård construction, while SHA-3 falls under ...
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Is it secure to hash an AES key?
Let's say I want a way of generating a deterministic public ID for a specific symmetric cryptographic key (AES, for example). Would it be secure to use SHA-3 (or SHAKE) to hash the key, and then ...
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How would Keccak attain a 512-bit security level?
I am well aware that the general consensus is that a hashing algorithm with a security of 512 bits is unnecessary, but I'm just curious about how that would be implemented for Keccak despite that.
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Why is SHA-3 a Sponge function?
A sponge function is supposed to be able to generate an arbitrary length of output. Yet, SHA3 (Bouncycastle) constrains me to choose an output length between 224, 256, 384, and 512. Evidently, these ...
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Strength of Hash obtained by XOR of parts of SHA3
I create a hash with SHA3-384. I split the resulting array into two. The first called head has the first 320 bits and the second called tail has the last 64 bits.
Next, I XOR head and tail. Which ...
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Hexadecimal and ASCII give different SHA3 hashes, why?
Hex and ASCII are encoded with the same binary code. Why is it that a message in ASCII and the same message in hexadecimal produce different hashes?
For example, the message ...
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1answer
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Use sha3 for passwords hashing
Is use of sha3 justifiable? Is sha3 better than sha2 in (m)any aspects?
P.S. I want to use hashing for passwords in a database
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What does this part of the SHA-3 algorithm mean?
I was reading through this paper and came across (pg. 11 of PDF, 5 of paper) the right_encode(x) and left_encode(x) pseudo-code ...
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What is an extendable output function?
The standardization of SHA-3 included the specification of two functions, SHAKE128 and SHAKE256. Both SHAKEs are referred to as extendable output functions, but what makes a function an extendable ...
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Cache Timing Attack SHA-3
I’ve been tinkering with SHA-3 for a little bit, and I have some questions regarding the applicability of cache timing attacks on this particular hash function. The two sub functions that I believe ...
