Unanswered Questions
2,544 questions with no upvoted or accepted answers
31
votes
0answers
1k views
Who first published the interest of more than two prime factors in RSA?
Multi-prime RSA is now a well known technique (described here): it uses $k>2$ distinct secret prime factors in the public RSA modulus, with the advantage that, using the CRT, we can gain a speed ...
31
votes
2answers
1k views
Hardness of finding mutual discrete logarithms of small generators in $\mathbb{Z}_p$
Suppose you want to select a prime $p$ such that finding e.g. $\log_2(3)$ in $\mathbb{Z}_p$ is expected to be either at least as hard as the general Discrete Logarithm Problem in $\mathbb{Z}_p$, or at ...
18
votes
0answers
607 views
Memory-hard password hash in practice?
Dan Boneh, Henry Corrigan-Gibbs, and Stuart Schechter have proposed Balloon Hashing: A Memory-Hard Function Providing Provable Protection Against Sequential Attacks (in proceedings of AsiaCrypt 2016). ...
15
votes
0answers
268 views
Adding bit constants to the key schedule to reduce rounds?
Bit constants are often added to the key schedule to reduce slide attacks. I have reviewed David Wagner's work, where he showed that the increased rounds in a Feistel network do not help if you have ...
14
votes
0answers
216 views
Fewest qubits required for the discrete logarithm problem and integer factorization
According to a paper from 2002, the most efficient circuit to factor an $n$-bit integer requires $2n+3$ qubits and $O(n^{3}\lg(n))$ elementary quantum gates, assuming ideal qubits. Later on, according ...
13
votes
1answer
410 views
Is Pohlig-Hellman Cipher the only option?
I am looking for a cipher which would allow something like this: E(E(M, a), b) = E(M, ab), where a and b are encryption keys, and ab is a combination of the keys that is impractical to separate into a ...
13
votes
0answers
278 views
Finding $x$ such that $g^x\bmod p<p/k$?
In a Schnorr group as used for DSA, of prime modulus $p$, prime order $q$, generator $g$ (with $p/g$ small), how can we efficiently exhibit an $x$ with $0<x<q$ such that $g^x\bmod p<p/k$, for ...
13
votes
0answers
233 views
Name of an archaic type of RSA padding (0BBBBBBB…)
In some legacy code, I encountered RSA signature padding in the following format (hexadecimal):
0B BB BB BB BB BB BB ... BB BB <hash>
Is there a name for ...
12
votes
0answers
629 views
Given a 'good' basis for a lattice, how can we solve the CVP?
I'm doing a little bit of reading about lattices. I read that if we can find a 'short' basis for our given lattice, we can solve CVP and SVP very efficiently. However, the paper didn't describe an ...
12
votes
0answers
156 views
Space complexity of quantum collision search?
Is there a known way to reduce the space complexity of quantum collision search (PDF) beyond what is offered by the built-in time-space tradeoff, while keeping the time complexity significantly below ...
11
votes
0answers
399 views
Potential Flaws With Lattice Based Cryptography?
From researching post-quantum cryptographic schemes it seems hash-based and lattice-based algorithms are the most promising (MQ-based seem to be covered by patents and have more potential unknowns ...
11
votes
0answers
2k views
Cracking a PRNG by observing ranks within groups of its output
Suppose that I am generating random numbers with Python's random module, so that there is a known random number generator (Mersenne Twister in this case). I've ...
11
votes
0answers
475 views
Efficient decoding of irreducible binary Goppa codes and the role of matrix P in McEliece cryptosystem
If we assume that the support for an irreducible binary Goppa code $\gamma_1, ..., \gamma_n$ is publicly known, when is it possible to efficiently decode the code? I know it's possible if one knows ...
10
votes
0answers
416 views
Crypto AG (Switzerland) - Which algorithms were used and how did the backdoors work?
Backstory
Crypto AG was a company located in Switzerland that specialized in communication security. They produced a number of encryption machines (some similar to the infamous Enigma) used for ...
10
votes
0answers
354 views
How Significant is the New Quasi-Polynomial-Time Attack on Fixed Characteristic Discrete Logarithms?
There is a new paper by Kleinjung and Wesolowski on eprint that claims and proves a new attack on the discrete logarithm problem in finite fixed characteristic fields in quasi-polynomial time.
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