I have recently read in a newspaper the claim " once quantum computers are sufficiently advanced, they will render current cybersecurity technologies completely ineffective ". As a civil servant "sufficiently expert" in this field, I feel it is my duty to point out that this claim is deeply wrong. I will do so at least in this web blog. Quantum computers and Post-quantum cryptography (PQC) Once so-called ‘ quantum computers ’ become available in practice, they will be capable of breaking certain cryptographic algorithms that have been widely used for many years and are still used today. For this reason, for years now, there has been a huge push worldwide to accelerate the transition to so-called ‘post-quantum cryptography’ (PQC): cryptographic algorithms that can be executed by the standard computers we already have today , but which cannot be ‘decrypted’ even by the quantum computers of the future . Various PQC algorithms have already been developed and standardise...