So What’s A Modulus In Post Quantum Cryptography?
If you are into cybersecurity or secure software development, you may have learned about public key encryption and of the methods that were created around the end of the 1970s and in the 1980s. Well, you may just have to learn some more theory — as the methods you learnt could be under threat from quantum computers.
So, if you want to start you learning about these new methods, then read on. If you are happy to live in a pre-post quantum world of public key encryption, then perhaps stop reading.
The (mod p) operation
In traditional public key encryption, we use a modulus to create a finite field. While it might sound complex, it actually quite a simple concept. For a finite field, we introduce a modulus, and which is normally a prime number. So with the prime number we basically determine the remainder from an integer divide, and then take the remainder as the result. For example, if we have a prime number of 17, we will have output values that range from 0 to 16:
5 (mod 17) = 6
19 (mod 17) = 2
100 (mod 17) = 15
The great thing with the (mod p) operation, is that we can still add, subtract, multiply and divide, and end up with the same result, such as:
