Is quantum key distribution an alternative to post-quantum cryptography?

For almost every company, no. Quantum key distribution (QKD) uses the physics of single photons, sent over dedicated fibre or free-space links, to agree a key in a way that reveals eavesdropping. It needs special hardware at both ends, works over limited distances unless trusted relay stations are added, and does not authenticate the two parties by itself, so it still needs classical or post-quantum signatures. Post-quantum cryptography, by contrast, is software that runs on the networks and devices you already have. European security agencies, including Germany's BSI, France's ANSSI and the Dutch NLNCSA, have published a joint position that treats post-quantum cryptography as the main path and QKD as suited at most to niche uses. The EU's quantum communication infrastructure, EuroQCI, serves specific governmental needs and is a separate matter from what a mid-sized company should buy. If a vendor offers QKD as the answer to harvest now, decrypt later for an ordinary office network, ask what it does that a hybrid TLSTLS: Transport Layer Security. The encryption that protects most internet traffic, such as HTTPS. or VPN configuration does not.

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