Just How Secure is Quantum Cryptography? This image illustrates the standard assumption made in quantum cryptography, namely that the devices, such as photon sources and detectors, used by the honest parties, “Alice” and “Bob,” are completely trusted (yellow boxes indicate the trusted region), whereas the channel connecting Alice and Bob may be controlled by an adversary. Credit: Renato Renner.

Just How Secure is Quantum Cryptography? This image illustrates the standard assumption made in quantum cryptography, namely that the devices, such as photon sources and detectors, used by the honest parties, “Alice” and “Bob,” are completely trusted (yellow boxes indicate the trusted region), whereas the channel connecting Alice and Bob may be controlled by an adversary. Credit: Renato Renner.