The future of public key cryptography will be post-quantum cryptography

By _Xiphera Blog

March 7, 2022

Quantum computing is a novel paradigm for computing that was introduced as a concept in the 1980s and has enjoyed a lot of attention in the recent years as the research and development for building actual quantum computers has started to bear fruit. Quantum computing holds great promise for solving some of the most difficult computational problems. It is expected to bring major advantages, for example, for drug development, weather forecasting, different kind of optimizations problems, etc. Unfortunately, quantum computing also has a darker side; If large enough quantum computers become reality, then they may solve the computational problems that are the basis of modern computer security.

Specifically, a quantum algorithm introduced by Peter Shor in the mid-1990s and subsequently called the Shor's algorithm can perform integer factorisation and find discrete logarithms in polynomial time (that is to say, significantly faster than what is possible with classical computers). RSA and Elliptic Curve Cryptography (ECC), which together cover practically all currently deployed public key cryptosystems, are based on integer factorisation and discrete logarithms, respectively. Consequently, quantum computing poses a threat to RSA and ECC and the security of the modern computation and communication infrastructure as a whole. The state-of-the-art of quantum computers is still far from being able break practical cryptosystems and certain difficult technical problems must be solved before quantum computers can be scaled to the sizes that pose a practical threat. Nevertheless, the threat of quantum computing must be taken seriously and it must be addressed pro-actively because often data needs to remain secure for decades and also rolling any new cryptosystems into practical use takes a long time.

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