One-way functions (OWF) are easy to compute, but hard to invert. They exists only if P$\ne$NP. Many cryptographic primitives are based on (or are implied by) the existence of one-way functions.
Questions tagged [one-way-functions]
51 questions
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Attack on hash functions that do not satisfy the one-way property
I am revising for a computer security course and I am stuck on one of the past questions. Here is it:
Alice ($A$) wants to send a short message $M$ to Bob ($B$) using a shared secret $S_{ab}$ to authenticate that the message has come from her. She…
sam
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Do one way function exist?
I was recently going through the Wiki page List of unsolved Problems in Computer Science.
There was a problem which I do not understand
Do one-way functions exist ? [Is public-key cryptography possible ?]
A one-way function is a function that is…
Atinesh Singh
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Length-preserving one-way functions
Unfortunately my background in computational complexity is still weak, but I am working on it.
As I understand, the question of existence of one-way functions is very important in the field.
Assume there are one way-functions, how it can be shown…
com
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If xor-ing a one way function with different input, is it still a one way function?
Suppose $f(x)$ is a one way function. What about $h(x)=f(x_1) \, \oplus \,f(x_2)$, where $x=x_1 || x_2$ and $\lvert x_1 \rvert = \lvert x_2\rvert$?
$\oplus$ is exclusive disjunction (xor)
$||$ is concatenation
$|u|$ is the length of $u$
Kate Green
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What will i obtain if i apply a xor-ing a one way function and it's input?
I know that a one-way function is informally a function that it's easy to compute but hard to invert.
If f(x) is a one way function the function $g(x) = x\oplus f(x)$ is a one-way function?
My intuition is that it's but i not really sure.
dbonadiman
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How to prove that existence of one-way functions implies P≠NP?
Wikipedia:
The existence of such one-way functions... would prove that the complexity classes P and NP are not equal.
How is this proved?
porton
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Any evidence that one way functions exist?
There is no known proof that one way functions exist. But what is the heuristic evidence that they exist?
I sometimes read that the existence of cryptography is heuristic evidence that they exist. E.g. the ciphertext from a block cipher like AES is…
user56834
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How to show composition of one way function is not such?
I was wondering how should I proceed in order to show that the composition of (say) two one-way functions (either weak or strong or both together) is not a one-way function?
Specifically: Say $f$ and $g$ are one-way functions (either weak or…
LMG
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Hardcore Bit proof for discrete log
I am studying Crypto and am trying to understand why discrete log creates is useful for creating a PRG. More specifically, I want to prove via reduction that $B(x)=(x
Cpt Wobbles
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Universal One-Way Functions
The Berman-Hartmanis conjecture discusses one-way functions (functions with hard to compute inverse functions).
As a step to solving the conjecture, if one-way functions could be reduced to a canonical or universal one-way function from which all…
user13675
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If a one-way functions (OWF) exist, then there exits a OWF that is computable in quadratic running time by a padding argument
I believe this question should be extremely easy but I am having a (embarrassing) hard time figuring out why its true if there exist OWF (computable in polynomial time) then there exits a OWF that is computed in $O(n^2)$.
This is what I…
Charlie Parker
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Using a proof-of-work system to discourage piracy or encourage donations
Background
A proof-of-work system allows one peer to prove to another peer that a certain amount of computational effort was performed.
In a network setting this can be used to throttle peer requests without needing to keep a precise track on the…
LateralFractal
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Polynomial-time algorithm with exponential space is eligible?
I'm curious about two things.
When we define the class called "probabilistic polynomial-time algorithm" in computer science, does it include polynomial-time algorithm with exponential space?
For example, when algorithm is considered to be given a…
euna
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How do you find the inverse of an arbitrary $f(x)$ if $f$ isn't one-way?
I'm considering the following definition of one-way functions:
Let $f : \{0,1\}^k \rightarrow \{0,1\}^k$ and $b : \{0,1\}^k \rightarrow \{0,1\}$ be computable in poly($k$) time. We say that $f$ is a one-way function with hard-core bit $b$ if, for…
Sebastian Oberhoff
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Understanding Incentive Compatibility of pooled Bitcoin Mining paper
I'm trying to understand the paper Incentive Compatibility of
Bitcoin Mining Pool Reward Functions (Schrijvers, Bonneau, Doneh and Roughgarden, in Financial Cryptography and Data
Security – FC 2016 Workshops, BITCOIN, 2016; PDF).
In page 3 Section…
T.Harish
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