For questions about hash functions: functions from a big set to a smaller one such that the same output $f(x_1)=f(x_2)$ for different input $x_1\ne x_2$ is unlikely, especially if $x_2$ differs from $x_1$ by a random error or is crafted by an adversary.
Questions tagged [hash-function]
245 questions
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Simple and fast homomorphic checksum - XOR MD5?
TL;DR; How bad is it to XOR MD5 checksums? Will this lose MD5's advantages and if so, what else can be used for making fast, online checksum on a key-value store with a good collision rate?
We got a key-value store and we want to implement a simple…
Kiril Kirov
- 205
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How to calculate Pool reward for Race of Work?
I invented a new concept called Race of Work. It's based on Proof of Work, except there is no difficulty. Instead, there is a predefined time in each hour that consider being Block time. During the block time all the miners trying to find the…
Ilya Gazman
- 1,440
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Is this function reversible?
I have a function which takes an integer from within a range (for example, 0-9999 with a range of 10,000) which outputs another integer within the same range. To my understanding, this is a perfect hash function. Each input within the range maps to…
Simon Cave
- 125
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Generating hash function from given hash table?
I need help with understanding the following problem:
In a factory, machines are making cars (1-n) along the production line.
One machine is making one part on the existing construction (part 1 is made by machine 1,...). Installation order of some…
user300047
- 179
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Calculation of the avalanche effect coefficient.
Given a strict avalanche criterion matrix/dependence matrix for a hash function,how do I calculate the avalanche coefficient for it.
I want to calculate a single parameter(value) which represents the amount of avalanche effect for the given hash…
user328743
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Does this function satisfy the Uniform Difference Property?
Does $h_{a,b}(x) = ((ax + b) \bmod 2^w)/2^{w-M}$ satisfy the Uniform Difference Property: given constant integers $w, M: w >= M$, and for any choice of distinct $x$ and $y$ in $[0, 2^w]$, $h(x) - h(y)$ is uniformly distributed over $[0, 2^M]$, given…
Demi
- 329
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A Hashing Problem
Hashing: You are to store objects identified by integers from [0..N − 1]. You expect never to have to store more than K objects. How would you design the hash function? Describe a general approach to design the hash function in terms of N and K. If…
Shammy
- 1,153
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general hash function question
The question: let it be two data structures that are represented by hash tables $T_1,T_2$ with chaining ($T_1,T_2$ are arrays of linked lists), and hash functions h1,h2 accordingly. Suppose that the distribution of keys is sufficiently uniform by…
John
- 341
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Elgamal signature scheme
Suppose that $(m, r, s)$ is a message signed with an Elgamal signature scheme. Choose $h$ with $(h, p − 1) = 1$, and let $r_1 ≡ r^h\pmod p$, $s_1 ≡ sr_1h^{−1}r^{−1}\pmod {p − 1}$, and $m_1 ≡ mr_1r^{−1}\pmod {p − 1}$. Show that $(m_1, r_1, s_1)$ is a…
mike russel
- 311