Location-Based Quantum Encryption
Location-based encryption—a system by which only a recipient in a specific location can decrypt the message—fails because location can be spoofed. Now a group of researchers has solved the problem in a quantum cryptography setting:
The research group has recently shown that if one sends quantum bits—the quantum equivalent of a bit—instead of only classical bits, a secure protocol can be obtained such that the location of a device cannot be spoofed. This, in turn, leads to a key-exchange protocol based solely on location.
The core idea behind the protocol is the “no-cloning” principle of quantum mechanics. By making a device give the responses of random challenges to several verifiers, the protocol ensures that multiple colluding devices cannot falsely prove any location. This is because an adversarial device can either store the quantum state of the challenge or send it to a colluding adversary, but not both.
Don’t expect this in a product anytime soon. Quantum cryptography is mostly theoretical and almost entirely laboratory-only. But as research, it’s great stuff. Paper here.