Comment by cycomanic
1 day ago
Controversial opinion, but many in the quantum community actively contribute to and take advantage of this confusion.
Prime example: The whole idea of QKD (Quantum Key Distribution), if you listen to many talks they often motivate the talk using Shor's algorithm and the idea that a quantum computer would possibly break many classical encryption algorithms in the future (that's so far still largely a theoretical result). They then sell QKD as the solution because it's "quantum secure", but QKD is a key distribution mechanism for symmetric encryption (which can't be broken by quantum algorithms). Moreover it's really just a physical layer "sensing" solution, where you can transmit data (over a special link) and detect if someone has listened in on your transmission.
So they sell a solution to the public key encryption possibly being broken by quantum computers in the future, but their solution can not replace public key encryption, because it can only secure a link between two predetermined endpoints. It's an dishonest marketing ploy.
One of the primary uses of public-key encryption is key exchange at the beginning of a session that is subsequently encrypted using symmetric encryption. That's how every TLS session works, because public-key encryption is too slow for large amounts of data. Since QKD is a solution for key exchange, it can replace public-key algorithms in this respect.
The other main application of public-key encryption is digital signatures, which is vital for certificate checking and identity verification in general. At first glance, it seems QKD won't solve that, as you said, but I haven't looked into quantum research relating to signatures.
Quantum computing and cryptography research is important, but are some researchers taking advantage of hype to stay funded by letting people think practical applications are closer than they really are? Possibly. Nonetheless, the research is important.