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 standardised. Furthermore, these algorithms are supported by common software and their use is already becoming widespread.
For example, the Microsoft Edge browser (the one I am using right now) supports PQC; Cloudflare Radar estimates that approximately 70% of the web traffic in Europe is already post-quantum encrypted (quickly growing: it was 40% one year ago).
It is therefore evident why the claim mentioned at the beginning of this blog post does not make any sense: cryptographic algorithms that cannot be broken by quantum computers are already in widespread use.
I could terminate this blog post here, but I feel obliged to make a few further points.
Quantum Key Distribution (QKD)
Among the huge number of research topics of scientific interest, one can certainly include the secure exchange of cryptographic keys with the so-called quantum key distribution (QKD).
QKD has two important properties: any attempt at interception will be immediately apparent and thus will invalidate the exchanged key; and, the secure exchange will not be decryptable by the future quantum computers.
These properties are sometimes summarized in the news as "unbreakable by hackers", "it enables complete security" and something alike.
Claims of this kind are deeply misleading, at best. One is more or less implicitly led to believe that once communication between two points defined in advance and already mutually authenticated (which is the starting scenario in QKD) is made secure, then we will enjoy a huge step forward in cybersecurity.
Well, this is definitely not the case. Just two remarks.
First, the MITRE ATT&CK framework categorizes attack techniques observed in real attack campaigns (I use this framework heavily in my Cybersecurity course at the Master Degree in Computer Engineering at UniTrieste). The current version lists 216 (two hundreds and sixteen) different attack techniques.
Even leaving aside that the "problem" solved by QKD is solved already, QKD could improve only 1 of the 44 (forty four) mitigations that defenders have to use (the one called "Encrypt Sensitive Information"). This mitigation may help in only 18 of the 216 attack techniques. Furthermore, by looking at these 18 attack techniques in detail, it is easy to realize that QKD might be of some help in no more than 4 or 5 of them (for example, QKD cannot be used for encrypting disks or for encrypting authentication tokens).
Second, I cannot think of any cybersecurity incident in the last years where a "strong encryption in communication" would have helped.
Not the Jaguar and Land Rover attack (October 2025), not Marks and Spencer (June 2025), not Co-op (June 2025), not the Irish Health Service (May 2021), not the global alluminium producer Norsk Hydro (June 2019), not the "Azienda Sanitaria in Abruzzo" (May 2023), not Toyota (February 2022)...I could go on and on, but I really cannot think of any recent incident in which QKD might have helped.
Appendix: Documents by some National Security Agencies
NSA
ENISA (European Union Agency for Cybersecurity)
France, Germany, The Netherlands, Sweden
- French Cybersecurity Agency (ANSSI)
- Federal Office for Information Security (BSI)
- Netherlands National Communications Security Agency (NLNCSA)
- Swedish National Communications Security Authority, Swedish Armed Forces
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