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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Using a bit sequence of zeros followed by one byte in Keccak
For what purpose it is not right to use a bit sequence of 2000+ zeros followed by one byte in Keccak? Is there a possible application of such input for Keccak? If yes, after which transformation?
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Outlook of trustworthiness of SHA-2
On the Wikipedia page of SHA-2, the following is written:
Currently, the best public attacks break preimage resistance for 52 out of 64 rounds of SHA-256 or 57 out of 80 rounds of SHA-512, and ...
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1answer
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Different inputs but able to generate consistent outputs across different SHA engines
Say I'm feeding in few thousand bits data (INPUT AAAA) into both SHA256 & SHA3 256 engines at the same time. (Both engines using different hashing architecture) and hence it will generate ...
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1answer
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Can you use a dynamic key and data size for KMAC?
I've asked before if some kind of canonical encoding should be used on the input parameters of SHA-3 before it could be used as replacement for HMAC.
However, if I read the current NIST specifications ...
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1answer
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Can a SHA3 engine be used to construct a Keccak implementation?
I am working on a cSHAKE-128 & cSHAKE-256 implementation that takes advantage of a number of hardware accelerators I have at my disposal, specifically for SHA-3 256/384/512 and SHAKE 128/256.
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1answer
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SHA3 hexadecimal paddig odd length string
Section B2 of FIPS-202 specification describes the Hexadecimal Form of Padding Bits which is basically the translation of the bit padding 0110*1. However at the beginning they suppose that the message ...
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1answer
63 views
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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2answers
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Are the common hash algorithms already dead? [closed]
I have one honestly question: How can we are so confident with the use of the common hash algorithms (nowadays there are so many pages with cracking tools: crackstation, gpuhash, etc) ?
Are we lost ...
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3answers
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Using sha3 as a deterministic source of psuedo-random bytes for xor encryption
The following code generates a deterministic stream of pseudo-random bytes, using SHA3.
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2answers
103 views
Is it possible to create a ciphersuite for TLS 1.3 using only the Keccak-sponge/duplex?
Now that Keccak has been chosen as SHA-3 we see that there have been defined quite a few related modes, including authenticated cipher modes, the KMAC message authentication mode, XOF's and whatnot. ...
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1answer
58 views
Does hashing PII in logs provide any real security?
I have PII in my logs that I would like to replace with hashes (e.g. sha3-256(salt + email)). The idea is that I can always go back to my logs and find all the log ...
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How are the Keccak rate and capacity bits determined at the beginning stage of the algorithm?
I'm learning about Keccak and am trying to understand more about the rate and capacity; specifically, how they are determined at ...
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1answer
34 views
How to use Botan to verify a web3 wallet/password?
The specification here seems quite clear, but unfortunately I'm still doing something wrong...
I have this (single small c++ file) repository which very straightforwardly follows the password/wallet ...
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2answers
126 views
How does KECCAK operate on a state array filled with zeros?
Im trying to implement a sponge in Java. The state starts out as an empty 200 byte array of all zeros. In the KMAC samples document from NIST, the following happens:
(black line is a pdf page break)
...
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1answer
129 views
Why HAIFA and sponge constructions are not prone to length extension attacks?
I was writing in a document about the flaws of the MD construction which pushed cryptographers to create different and more robust constructions. However, I don't know why HAIFA and Sponge ...
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2answers
741 views
What is the sponge construction in simple terms?
I suggested to my client to use SHA3 instead of SHA2. I know that SHA3 is based on Keccak algorithm which won the NIST's competition.
I want to explain the structure of sponge functions in very simple ...
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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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2answers
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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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1answer
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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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2answers
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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
63 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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2answers
179 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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2answers
218 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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1answer
79 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
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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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1answer
75 views
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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3answers
2k views
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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2answers
268 views
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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4answers
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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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1answer
288 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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2answers
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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
802 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
107 views
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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2answers
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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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2answers
352 views
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
315 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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1answer
306 views
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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2answers
398 views
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
378 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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1answer
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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
316 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
330 views
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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2answers
476 views
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. ...
