- #1
stroustroup
- 14
- 0
Is there an algorithm which, given n, returns an integer x such that 2 has order n modulo x (i.e, 2^n = 1 mod x and n is the smallest positive solution)? Is there any such algorithm which runs faster than factoring n?
Finding such a number x is important in number theory and cryptography, as it allows for efficient computation of discrete logarithms and plays a crucial role in the security of many cryptographic algorithms.
The order of 2 mod x is the smallest positive integer n such that 2^n mod x is congruent to 1. The multiplicative order of 2 mod x is the smallest positive integer k such that 2^k mod x is congruent to 1 for all integers relatively prime to x. Therefore, the order of 2 mod x is always a factor of the multiplicative order of 2 mod x.
There are various algorithms and techniques for finding such a number x, including the use of primitive roots, prime factorization, and the Chinese Remainder Theorem. The most efficient method will depend on the specific values of n and x.
Aside from its importance in number theory and cryptography, this problem has applications in various areas such as coding theory, error-correcting codes, and pseudorandom number generation.
This problem is an active area of research in mathematics and computer science, with ongoing efforts to develop more efficient algorithms and to understand the relationships between different values of n and x. There are also applications of this problem in other fields such as physics, biology, and economics, which continue to drive research in this area.