Questions tagged [2nd-preimage-resistance]

Difficulty of finding another input string that hashes to the same value as a given string

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Second-preimage attack on Streebog

Could attack similar to described in paper "The Usage of Counter Revisited: Second-Preimage Attack on New Russian Standardized Hash Function" be applied, if Streebog used Matyas-Meyer-Oseas ...
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Is there a feasible preimage attack for any hash function (no matter how deprecated) today?

Has there ever been a hash function that was actually used in the field, no matter how long ago, for which there is now a feasible preimage attack? All hashes that are nowadays considered 'broken' (...
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Finding second-preimage to this use of weak hash

$h'(x) := h(a_1 \parallel x \parallel b_1) \parallel h(a_2 \parallel x \parallel b_2) \parallel h(a_3 \parallel x \parallel b_3) \parallel \dots \parallel h(a_k \parallel x \parallel b_k)$ $a_i$ and $...
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Finding multiple smaller collisions equal work as finding a bigger collision?

Problem A: I receive two hash digests $H(x), H(y)$ and the corresponding preimages $(x, y)$. $H$ is a 128-bit cryptographic hash function: $H: \{0,1\}^{*} \longrightarrow \{0, 1\}^{128}$ I need to ...
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Public Key Fingerprint: Preimage Resistance

In my system, “resources” are granted operational certificates signed by a particular CA. Each resource has a unique public/private key pair that it generates once. The operational cert granted by the ...
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Application of cryptographic hash functions which do not require collision resistance property

I can not understand why collision resistance of a cryptographic hash function is not required for some applications. for example, if we store the trusted hash of a file or program, and later when we ...
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114 views

Can we use a Merkle Tree structure to reduce digest size?

A 2nd preimage attack is possible on the standard Merkle tree as pictured below. I'm aware that we can add identifiers (to differentiate nodes) to the input of each hash as discussed in the link. If ...
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What are the “costs” to find a pre-image, weak collision, or strong collision?

For a secure, n-bit hash function, what are the “costs” to find a pre-image, weak collision, or strong collision?
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finding second pseudo preimage faster than brute force

As far as I know finding second preimage of a hash function is almost as hard as finding preimage. But I want to know that is there any way to finding second pseudo preimage faster than brute force? I ...
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1answer
289 views

Practicality of a certain hash function

Consider the following hash function: $$(V\cdot A + V\cdot B)^2 \bmod C$$ $A, B,$ and $C$ are large primes. $V$ is the value to be hashed and is guaranteed to contain at least as many bits as the ...
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343 views

Why this isn't second preimage resistance?

I've been reading on preimage resistance and trying out few examples for the same and I'm trying to figure out why the following hash function does not have the second preimage resistance and any ...
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Is an HMAC based on a second-preimage resistant hash function always unforgeable?

If hash function is collision-resistant, then its associated HMAC is always unforgeable. But suppose that a hash function is only second-preimage resistant, not necessarily collision-resistant. Then ...
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Do hash functions for digital signatures need to be preimage resistant?

I understand that hash functions used for hashing a document or some data before signing it, needs to be collision resistant and 2nd pre-image resistance. Otherwise an adversary could "look" ...
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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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Computational requirements for breaking SHA-256?

Let's define "breaking" a hash function $H$ as being threefold (corresponding to the main properties of a cryptographic hash function): preimage attacks to get $m$ knowing $H(m)$ second-preimage ...
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Second preimage attack complexity when the digest is malleable

An attacker has a hash $h$ and a message $m$. He wants to find $m^\prime$ with the same length as $m$ which hashes to $h^\prime$. However, $m^\prime$ can only differ from $m$ in the 1 bits (i.e. ...
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Are My Answers to This Hash Question Correct?

Question When determining the security of a hash system, the cryptanalyst tries the following attacks. (a) If the attacker is NOT allowed to modify the original message, determine the number of hash ...
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The difference between being not strongly collision resistant, and not weakly collision resistant?

So I understand the two concepts: (Strong) collision resistance: it is infeasible to find a pair $x \neq x'$ such that $h(x) = h(x')$ Weak collision resistance / 2nd-preimage resistance: for all $x \...
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How to find k-way second preimages

For example: Assuming someone has found a second preimage for SHA-256. In other words, for SHA256(M1)=H, someone has found M2 which SHA256(M2)=H Now, is it possible to generate k-way second ...
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Why is this attack complexity equal that exact number of bit operations?

in the this paper,section 3,autors attack hamsi-256. Im trying to make a parametrized version, so i need to understand how do they estimate the complexity of attack in bit operations,that reads as ...
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Swapping a single bit inside a 40 bytes inputs fed to keccak256. Is it safe to assume no change in the first 20 bytes can result in the same hash?

I have the following data (represented as hex from binary below) where the lower bytes is controlled by attacker in the second case : ...
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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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Hash-based signature scheme XMSS/LMS susceptible to preimage/second preimage attack?

Are the quantum secure hash based signatures (XMSS/LMS) susceptible to preimage/second preimage attack?
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1answer
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Question about second preimage resistance of hash function combiner

Let $\Pi=(Gen_1,H_1)$ and $\Pi=(Gen_2,H_2)$ be two hash functions. Define $(Gen, H)$ so that $Gen$ runs $Gen_1$ and $Gen_2$ obtaining $s_1$ and $s_2$ respectively. Then let $H^{s_1,s_2}(x)=H^{s_1}(x)\|...
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1answer
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Cryptographic hash function based on logistic map?

Is there any secure cryptographic hash function based on the logistic map?
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Bitmasks or seed along with public key in WOTS+ post-quantum signatures

The state of the art hash-based post-quantum signature schemes, like Sphincs and XMSS, are using variations of WOTS (Winternitz OTS), like WOTS+, that require extra random bitmasks along with the ...
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Hashing based on the discrete logarithm problem

At a first look, one could use the elliptic curve discrete logarithm problem to grant for the onewayness of $H(x)=x*G$ (where $G$ is the generator point of the cyclic subgroup). Additionally, $H(x)$ ...
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collisions on hash functions

Why do we say that collision-resistance is a "harder" property than second pre-image for hash functions whereas if you have an attack on the second pre-image then you find a collision ? Moreover, a ...
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Security implications of slow-by-design hashes on relative security vs. hash size

Would it be true to say that that one can get away with much smaller cryptographic hashes if the hashing algorithm is slow and expensive by design? Example: let's say you want 128-bit hashes. This is ...
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1answer
754 views

How can I determine if a hash function is secure?

I'm doing an exam in computer security and I encountered this problem which I'm unsure of how to attack properly. Should I get down and dirty with the Hash function on paper or is there a more general ...
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775 views

Difference between second pre-image resistance attack and collision attack

According to my understanding of hashing algorithms -: Collision attack is an attack wherein we have a hash(x) and we try to find hash(y) such that x!=y while hash(x)=hash(y). Second pre-image ...
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Winternitz One time signature security

There are two versions of Winternitz-One time signature scheme, $W-OTS$ and $W-OTS^+$ Security of both is as following $W-OTS$ is strongly unforgeable under chosen message attacks if $F$ is a ...
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How many hash functions must Bob compute to find a solution?

Alice proposes the following puzzle to be completed. Let m be the body of the email message, let a be the recipient’s email address, let H( )be the hash function SHA3-256, ...
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Difficulty of collision vs preimage vs second-preimage attacks

It seems at first glance that brute-forcing a collision would be exactly as difficult for all of them. They all (I would expect) work like this: select a hash value, and then try messages to get an ...
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Second Preimages on n-bit Hash Functions by John Kelsey and Bruce Schneier

I read your https://www.schneier.com/academic/paperfiles/paper-preimages.pdf And found there: «3.2 A Generic Technique: Multicollisions of Different Lengths» <...
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usefulness of a collision attack that's not also a 2nd pre-image attack

So my understanding is that if we've got some hash function $H$ then a 2nd pre-image attack is one where given a message-hash pair $(m, H(m))$ we can find some $m' \neq m : H(m') = H(m)$, while a ...
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Is MD5 second-preimage resistant when used only on FIXED length messages?

I fully realize that MD5 should not be used in any new project, but in my particular situation I have severe CPU performance issues, so MD5 is convenient. I have read a lot about MD5 security for this ...
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Does collision resistance imply (or not) second-preimage resistance?

I've seen contradictory results. Sometimes hash functions are collision-resistant but not necessarily second-preimage resistant. I've seen this kind of things in papers from Bart Preneel: “Security ...
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Why does second pre-image resistance imply pre-image resistance? [duplicate]

Definitions here: Pre-image resistance Given a hash value h it should be difficult to find any message m such that ...
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1answer
851 views

Why do different applications of hash functions demand different properties of the hash function?

A strong cryptographic hash function in general must guarantee several properties, including: Preimage resistance, second preimage resistance and collision resistance. It turns out, however, that ...
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Why is Pearson hash not used as a cryptographic hash?

The original algorithm produces 1 byte long hash and is (of course) not suitable for cryptography use. But according to wikipedia, it is possible and easy to produce Pearson hash of any length, simply ...
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429 views

Create a potential input for sha-256 hash given a substring of input?

Let's say I'm given a specific SHA-256 hash. Further assume that the SHA-256 input, that yielded this hash contained a known sub-string. Is there a way to find the input (containing the specific ...
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1answer
246 views

Does absence of second pre-image resistance infer absence of pre-image resistance?

Talking about hash functions, I know the hierarchy is as follows: Pre-image resistance Second pre-image resistance Collision resistance Where each property implies the one before it so 2nd pre-...
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1answer
288 views

Determining collision resistance of a function?

I am having trouble trying to understand if the function is collision resistant. As I understand it, preimage resistance means that it is hard for an adversary to find two messages that produce the ...
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1answer
538 views

What is the complexity to break second preimage resistance?

In the context an of hash functions we have three required properties. Preimage resistance Second preimage resistance Collision resistance. The bounds for Pre image collision is $O(2^{n-1})$, the ...
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Effect of message length on collision attacks

I know that message collisions are supposed to be hard to calculate for a good cryptographic hash. Given 1k worth of data, it's hard to find another 1k worth of data that collides with the same hash. ...
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Computational feasible to reverse MD5SUM?

This might be out of ignorance, I apologize, but how complex of a problem might it be to generate a file of size $N$ whose MD5SUM is $X$? For example, ...
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1answer
586 views

Fast 128-bit MAC with second preimage resistance?

I have an application that needs a fast 128-bit MAC to guarantee message authenticity in a protocol. I would like to reuse this MAC value as a binding identifier, so that even those who know the key ...
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1answer
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Has there ever been more then a theoretical difference between preimage resistance and second preimage resistance?

In other words, has there ever been a point in time in which having the content of a message has actually helped break a hash function?
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Does SipHash have 64 bit (second) preimage security?

I was not able to find an explicit statement about the first and second preimage security of SipHash-2-4 or SipHash-4-8 anywhere. I think it should be 64 bits, but I'd feel safer if somebody who has ...