POST QUANTUM CRPTOGRAPHY

Subject: Science & tech

Concept:

• Classical computers use classical bits that can take the value 0 or 1, allowing for a binary system to be set up and the lowest level of computer language is done manipulating these bits.
• A Quantum Computer uses qubit on the other hand can exist as a superposition of two states 0 and 1. So if you have an n-qubit number, it can exist as a superposition of 2n states. This also allows for immense amount of parallel processing.
• Post quantum cryptography – a field which deals with additional possibilities offered by a quantum system, which goes beyond being able to break the integer factor code.

Enter lattices

• One of the main contenders for a mathematical problem that is hard for the quantum computer to crack is the so-called shortest vector problem.
• This involves lattices. Lattices are regular arrangement of points in space; examples in nature include honeycombs and all crystalline solids, like common salt.
• A line of regularly spaced points is a lattice in one dimension, and a crystal of salt is a three-dimensional lattice. Mathematically, we can extend this construction to 5, 10 or even 500 dimensions.
• At this magnitude, it becomes in theory a “hard” problem for a quantum computer to calculate the shortest vector from one point to any other point. This problem can therefore be used to construct “locks” that can even withstand a quantum attack.
• Post Quantum Cryptography provides new methods to construct such encryption schemes which are secure against quantum computers.