Post Quantum Cryptography vs Quantum Cryptography

Quantum computing has made significant developments recently and there has been quantum supremacy meaning that it is proven that the existing quantum computers are faster than the fastest non-quantum computers that we have right now. Quantum computing refers to the idea of using quantum bits (physically related tiny particles) to make computations instead of normal electricity. One of the most effective applications of quantum computers is traditional cryptography- decryption, in particular. There are two important topics when it comes to the discussion of using quantum computing in cryptography and this article is about their differences: post-quantum cryptography and quantum cryptography and they are very different things.

Post-Quantum cryptography refers to the idea that traditional cryptography, if weak enough, can be broken by quantum computers while electric computers cannot break them and these weak cryptography protocols need to be updated. For example, the regularly used AES128 bit encryption can be broken easily by a quantum computer. Then, Post-Quantum cryptography says, “Use AES256 bit encryption because it is quantum-proof”.

Quantum cryptography, on the other hand, refers to the concept of using quantum computing to encrypt information. Information can be sent through quantum-entangled photons between two separate quantum computers and if the information gets intercepted or read by anyone else, it can be detected.