Skip to main content
New
Stack Overflow Jobs powered by Indeed: A job site that puts thousands of tech jobs at your fingertips (U.S. only). Search jobs

Questions tagged [shors-algorithm]

Shor’s algorithm is famous for factoring integers in polynomial time. Since the best-known classical algorithm requires superpolynomial time to factor the product of two primes, the widely used cryptosystem, RSA, relies on factoring being impossible for large enough integers.

Filter by
Sorted by
Tagged with
11 votes
4 answers
8k views

How will the world learn that Q-Day has arrived?

I wonder how the world will come to know that scalable, fully fault-tolerant quantum computers capable of running Shor's algorithm have arrived. The day when this happens has been referred to as "...
Mark S's user avatar
  • 289
3 votes
1 answer
679 views

Are some RSA moduli more resistant than others to Shor's factorization algorithm?

Does there exist a semi-prime integer $n$ (e.g., an RSA modulus) such that the order of every element in the multiplicative group modulo $n$ is equal to the order of the full group modulo $n$? If so, ...
divaconhamdip's user avatar
7 votes
0 answers
285 views

Noisy Quantum Gates Spoil Shor's Factorization Attack

Update: In Lipton and Regan's blog, Scott Aaranson and Craig Gidney have commented that the results are not unexpected and also not a deal-breaker in that dealing with this type of noise is already ...
kodlu's user avatar
  • 22.6k
-7 votes
1 answer
126 views

Are Schnorr's algorithm really subject to q-computer attacks?

I was wondering whether quantum-computers really break Schnorr's signature scheme. Schor's algorithm works via the quantum Fourier transform, which reveals the cycle time and thus phi. However, with a ...
user avatar
0 votes
1 answer
103 views

Would it be technically possible to use hundreds of computer processors together to work on an algorithm like the Shor's algorithm and break RSA?

Would it be technically possible to use hundreds of computer processors together to work on an algorithm like the Shor's algorithm and break RSA? I've been reading about the crazy amount of qubits ...
Yuniel G's user avatar
1 vote
3 answers
179 views

Why can't we just increase the bit length to counteract shor's algorithm?

I know that it sounds like a very stupid question but if Shor's algorithm has a complexity of roughly $n^3$ why cant we just increase the bit size until the time for the algorithm to run is ...
HarryFoster1812's user avatar
4 votes
2 answers
939 views

How could ECDSA be broken with prime factorization through Shor's Algorithm?

could anyone help me understand how is ECDSA broken using Shor's Algorithm? All the papers I find are too complex to understand, and even though I feel I understand some concepts, some others are a ...
Pau T's user avatar
  • 61
19 votes
1 answer
5k views

Will IBM's Condor quantum processor run Shor's Algorithm to crack a 256-bit Elliptic Curve key?

Yesterday IBM announced that they have a 433 bit quantum computer, called Osprey. There is nothing in the press releases I can find that says whether it can or cannot run Shor's Algorithm. They also ...
Simon G.'s user avatar
  • 343
1 vote
1 answer
84 views

Can Shor's algorithm factor over finite fields/rings/groups?

Shor's algorithm can (efficiently) solve equations of the form: $$n = pq$$ and $$n = x^{2} + y^{2}$$ This question is simple: Can Shor's algorithm solve these equations in polynomial time when they ...
anon's user avatar
  • 45
3 votes
1 answer
143 views

Can Shor's algorithm factor over the gaussian integers?

This is related to this question about solving the following expression: $$x^{2} + y^{2}$$ This can be factored over the gaussian integers as $$(x + iy)(x - iy)$$ If one could factor a sum of two ...
anon's user avatar
  • 45
1 vote
1 answer
654 views

Shor's algorithm and ECDSA in Bitcoin - why is finding the private key still difficult when we know the base point?

I'm learning about Shor's algorithm and how it can be applied to break ECDSA. I've clearly missed something basic here - I thought I understood that the challenge ECDSA presented was to find the ...
compp's user avatar
  • 13
1 vote
2 answers
396 views

Using Shor's algorithm to access RSA messages without factoring

Most of the time people forgot that the real aim of the adversary against encryption is accessing the message. For example, in the RSA case, we talk about the factoring of the modulus to reach the ...
kelalaka's user avatar
  • 48.7k
6 votes
2 answers
193 views

Why doesn't this factoring to order-finding reduction work?

Scott Aaronson likes to motivate the factoring-to-period-finding algorithm used inside Shor's algorithm as follows. Now, I want you to step back and think about what this means. It means that, if we ...
panto's user avatar
  • 63
4 votes
3 answers
375 views

Period finding for Quantum Computers

Shor's algorithm shows how a quantum computer (with sufficiently many qubits) can solve the factorization problem efficiently. Also the discrete logarithm problem can be solved efficiently with such a ...
Marc's user avatar
  • 317
2 votes
1 answer
136 views

Is RSA-OAEP secure against Shor's factoring algorithm

I've seen in this answer Can Shor's algorithm compromise RSA when both the public and private key are secret? that if textbook RSA is used (deterministic) the Shor's algorithm can reak it. However, if ...
Yunus Karakaya's user avatar
1 vote
1 answer
159 views

Implications of Shor's algorithm on $F_{2^m}$ elliptic curves and GHASH

The security of elliptic curves depends on the difficulty of the discrete logarithm problem. Should Shor's Algorithm ever prove viable then elliptic curves would cease to offer any useful security ...
neubert's user avatar
  • 2,937
6 votes
1 answer
240 views

What is the best strategy to avoid getting even orders in Shor's algorithm?

I do understand Shor's algorithm wants the order of an element to be even so that it can use the factoring identity and find a non-trivial factor. But is there a relationship between safe primes and ...
user45491's user avatar
  • 409
9 votes
3 answers
984 views

Can Shor's algorithm factor multi-prime numbers?

I know that Shor's algorithm can factor semi-primes ($N = p \times q \space, \{p, \space q \in \Bbb{P} \space \vert \space p, \space q \gt 0 \} $). Assuming that all prime numbers are so large that ...
AleksanderCH's user avatar
  • 6,462
8 votes
0 answers
225 views

Time-memory tradeoffs in Shor's algorithm

Can a quantum computer with insufficient qubits to factor an integer of a given size make any progress in factoring it? For example, what if a quantum computer is only one qubit short of what is ...
forest's user avatar
  • 15.3k
1 vote
1 answer
584 views

Negative time complexity?

Just finishing an investigation into Shor's algorithm, and the following equation, $$ O\big(\big(\log N\big)^2 \big(\log \log N\big)\big(\log \log \log N\big)\big) $$ is given for its time complexity. ...
John Miller's user avatar
35 votes
2 answers
12k views

Largest integer factored by Shor's algorithm?

I'm studying Shor's quantum factoring algorithm. I was wondering what the largest integer is which they were able to factor with a small quantum computer. Does anybody have an idea about this?
Robbe Motmans's user avatar
2 votes
3 answers
326 views

Explaining RSA to non-scientists

I am to give a small lecture on quantum computing in a months' time and I want to shortly give intuition to the fact that Shor's algorithm shows that quantum computers will break RSA. Ideally, I would ...
user3231247's user avatar
2 votes
1 answer
644 views

Shor's algorithm for discrete log and periodic function

I am wondering about the following well-known problem: Let $p$ is a prime number, $g$ is a generator of $(\mathbb{Z}/p\mathbb{Z})^\times$, $b \in (\mathbb{Z}/p\mathbb{Z})^\times$. Find $x$ - an ...
Ivan's user avatar
  • 145
7 votes
1 answer
4k views

How can Shor's Algorithm be applied to ECC?

I have not found a specific answer to this question on here. Shor's algorithm can be used to factorize a large (semi)prime $N$ by reducing the task to period-finding of a function $f(x)=x^a$ mod $N$. ...
indiscreteLog's user avatar
2 votes
1 answer
1k views

Shor's algorithm for elliptic curve discrete logarithm problem

Could someone write Shor's algorithm for solving the discrete logarithm problem and how it could apply to elliptic curves in a few, easy to understand steps? I have a basic understanding of quantum ...
Neeraj's user avatar
  • 21
7 votes
1 answer
616 views

What does Shor's algorithm tell us about the complexity class of RSA and the DLP?

If quantum computers operate in BQP and (using Shor's algorithm) they are able to factor large integers and break the discrete log problem, what does that tell us about the complexity class of these ...
Sebastian's user avatar
  • 461
8 votes
1 answer
8k views

Using Shor's algorithm to solve the discrete logarithm problem

I have read about Shor's algorithm and my understanding is that it can be used to factor large numbers efficiently. Can Shor's algorithm, though, be used to solve this problem: Find the number $n$ ...
Mathew's user avatar
  • 325
11 votes
1 answer
1k views

Can Shor's algorithm compromise RSA when both the public and private key are secret?

If RSA is to create a public-private key pair and encryption is performed on plain test P to create ciphertext C, given P and C could Shor's algorithm be used to find either of the public and private ...
Mathew's user avatar
  • 325
9 votes
1 answer
948 views

Are post-quantum cryptographic ciphers *also* secure if the P=NP conjecture holds true?

First of all, I only understand the P versus NP debate on a rather shallow level as I am not a computer scientist. So perhaps the answer to the question is straightforward but if not, I would be ...
jayann's user avatar
  • 475
4 votes
1 answer
280 views

Shor's Algorithm Values

I'm studing Shor's algorithm, and I have a question regarding the following step: $$a^r -1 = (a^{r/2}+1)(a^{r/2}-1)=0 \pmod n$$ What would be the result if ${r/2}$ was -1? This will mean it's going to ...
Scarl's user avatar
  • 445
13 votes
1 answer
2k views

What is the difference between Shor's algorithm for factoring and Shor's algorithm for logarithms?

There is a paper from Peter W. Shor from 1994: Algorithms for Quantum Computation: Discrete Logarithms and Factoring, and I have a question about it and the algorithms presented. For integer ...
osgx's user avatar
  • 550
24 votes
1 answer
16k views

In layman's terms, how does Shor's algorithm work?

I've just been reading up on Shor's algorithm, and I find it both fascinating and baffling. I don't understand much about it, other than that it can factor semiprimes in polynomial time. Could someone ...
Polynomial's user avatar
  • 3,527