Linked Questions

0 votes
0 answers

How can I calculate the probability of collisions of a hashing algorithm? [duplicate]

I'm pulling a “Dave” and I'm designing my own hashing algorithm. Not that I intend to use it, I'm not certifiable or anything, I just want the challenge of creating something. I'm not going to get ...
Andrew Cobb's user avatar
15 votes
1 answer

Are hash functions strong against quantum cryptanalysis and/or independent enough of mathematics?

I work on ethereum and other blockchain technologies. And seeing that quantum pc's are someday going to see the light I have some questions / doubts. I was wondering if hash functions are strong ...
CPereez19's user avatar
  • 325
10 votes
2 answers

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 ...
Kishan Kishore's user avatar
10 votes
2 answers

Just how surjective is a cryptographic hash like SHA-1?

From “Are common cryptographic hashes bijective when hashing a single block of the same size as the output” and “How is injective, inverse, surjective & oneway related to cryptography”, it is ...
Paul Uszak's user avatar
  • 15.4k
6 votes
2 answers

Proof that MAC and hash composition is insecure

Let $F$ be a secure PRF and $H$ a universal hash function. How can I exhibit a pair $(F,H)$ whose composition $$S'((k_1, k_2), m) = F(k_2, H(k_1,m))$$ is an insecure MAC (or an insecure PRF, since a ...
Daniel's user avatar
  • 457
1 vote
2 answers

Does the double-hash H(H(x)) have greater collision probability than H(x)?

Let $H$ be a collision resistant hash function and $P_c[H](S)$ the collision probability about a sample set $S$ of input elements (eg. random numbers). It increases with double hash? That is, $P_c[H\...
Peter Krauss's user avatar
7 votes
1 answer

How to improve long-term duration of standard checksum for authenticity purposes?

Official CMS's of Government gazettes (in the third world), need to publish the checksum of each article and each cited external documentin (eg. full-text contracts) in a permanent support medium like ...
Peter Krauss's user avatar
5 votes
1 answer

What is perfect collision-resistence in probability terms?

update: removed lots of stupidity... sorry. I didn't know I can be this stupid but I achieved it. 1. Goal Let $\mathcal{D}$ be the universal space of our plain data. Our goal is to find a function $...
caveman's user avatar
  • 573
1 vote
1 answer

Is exponentiation of a fixed generator modulo a prime collision-resistant?

Let $p$ be a prime number, and $g$ a generator of $\mathbb Z/p\mathbb Z$. For a message $m$, define the hash function $$h(m) = g^m \pmod p.$$ Is $h$ collision-resistant?
mariyana.'s user avatar
  • 113
4 votes
1 answer

Is there an information theoretic equivalent of a trap door collision free function?

Warning: Possibly ill-posed question. I'm using the following definition from a recent paper available here. I believe their terminology is slightly different but reproduce my understanding of it ...
user1936752's user avatar
0 votes
1 answer

The collision rate probability decreases when using compression?

Some standard compression procedures, like the IANA's gzip provided by HTTP protocol, will consume CPU-time anyway... So we can reuse compressed file, $Z(x)$, in the checksum procedure. That is, we ...
Peter Krauss's user avatar