Quantum Cryptography vs Post-Quantum Cryptography

Originally published at https://www.amarchenkova.com on July 5, 2020.

With interest growing in developing universal quantum computers, examining post quantum algorithms and quantum cryptography that can replace modern cryptosystems is of vital importance to the security of our data in a world where a large scale, fault tolerant quantum computer exists.

Shor’s algorithm is the killer algorithm for cryptography. But having a quantum computer large enough to run this algorithm is still many years away. While some scientists argue that a quantum computer that can run Shor’s algorithm will never be possible to build, since it requires millions of qubits, others believe it’s inevitable and that we need to start preparing for this future.

There are two approaches. One is post-quantum cryptography, which is a new set of standard of classical cryptographic algorithms, and the other is quantum cryptography, which uses the properties of quantum mechanics to secure data. Both may have a place in the future of secure communication, but they work fundamentally differently.

Post-Quantum Cryptography

Post-quantum cryptography is classical cryptography that stands up to the attacks of a large quantum computer. It does not use any quantum properties. It…