Linked Questions

39 votes
3 answers
21k views

Are cryptographic hash functions quantum secure?

I was reading a paper related to post quantum cryptography. It says that RSA, ECC and ElGamal encryption schemes would be obsolete with the advent of quantum computers. But the hash functions can ...
user avatar
14 votes
2 answers
4k views

Is SipHash cryptographically secure?

I'm evaluating different hash algorithms for use in my application. One of the kind of algorithms I am looking at are cryptographically secure ones to protect against DOS attacks. SipHash seems ...
GBleaney's user avatar
  • 243
7 votes
3 answers
2k views

Will cryptanalysis always stay a relevant topic?

I hope this doesn't look like a silly question. In an age where our current cryptography is often impossible to crack when properly implemented and used, would we be able to decipher anything, for ...
Katoptriss's user avatar
11 votes
1 answer
1k views

Collision resistance of hash function built on modular exponentiation

Consider the following hash function family for hashing integers: $Gen(1^k)$: generate 2 $k$-bit primes p,q. Let $n = pq$. Choose random $y \rightarrow QR_n$ and output $n,y$. $H_{(n,y)}(x) = y^x \...
chelsea's user avatar
  • 404
5 votes
1 answer
1k views

Is there are a metric based on collisions to compare bad hash functions?

Bad hash functions are not so perfect as in the "general collision probability" hypothesis... And a general concept of "collision resistence" not need the constraint of independence between the ...
Peter Krauss's user avatar
3 votes
1 answer
841 views

How is pre-image resistance defined, formally?

Earlier today, forest asked in our chat, The Side Channel whether the definition of first pre-image security actually requires that an input that evaluates to the challenge hash result must be known ...
SEJPM's user avatar
  • 46k
3 votes
1 answer
2k views

How resistant are stream ciphers like Salsa20 or ChaCha in a post-quantum world?

What kind of quantum computer would be required, if it is possible to break such ciphers?
Bobisnotyouruncle's user avatar
-1 votes
2 answers
3k views

(strong) collision resistance Example

I'm studying Cryptography & Network Security. It has the following example for collision resistance: "Suppose Bob writes an IOU message, sends it to Alice, and she signs it. Bob finds two ...
NoNameDefined's user avatar
3 votes
4 answers
1k views

Find some hash function with deliberate collisions

I guess this should be well known (or trivially desperate), but I couldn't find any reference. I have a small number (say $k=15$) of messages $m_i$ ,$i=1\cdots k$ (they are fixed length and short, ...
leonbloy's user avatar
  • 131
0 votes
1 answer
516 views

How to use cryptography to assure data integrity?

I only understand assurance of integrity using a hash function. How to use cryptograpy to assure data integrity?
Ed S's user avatar
  • 125
2 votes
1 answer
374 views

Does an information-theoretically secure hash function exist?

Does an information theoretically secure hash function exist? (By exist I mean is discovered/invented and implemented, not whether it could exist.)
09182736471890's user avatar
1 vote
1 answer
170 views

Can NORX be used as a general purpose hash function?

In general terms, NORX works combining a cryptographic hash function and an stream cipher. At the end of an encryption operation you end with a ciphered message plus its authenticated hash. If you ...
user3368561's user avatar
2 votes
2 answers
243 views

Given a hash function; assuming domain % codomain = 0 and uniform collision distribution; how is entropy lost by collisions (not output truncation)?

Assuming our domain and codomain both have 4 elements, the uniform distribution of inputs to outputs means the function is injective. It is widely agreed that randomly selecting a domain element ...
Gratis's user avatar
  • 187
0 votes
1 answer
73 views

Are hashes only used to confirm data integrity when used for distributed ledgers?

I have a couple questions related to hashing and data. Please let me know if the questions I have are too broad for this site, or if clarification is needed. I have read a lot about hashing as it ...
W. Churchill's user avatar