Abstract: Trusted nodes in a network perform secure out-of-band symmetric encryption key delivery to user devices. A first trusted node receives a request from a first user device to deliver symmetric encryption keys to the first user device and a second user device, as a pair of user devices. The first trusted node delivers a second symmetric encryption key to the second user device, via trusted nodes. The first trusted node receives confirmation of delivery of the second symmetric encryption key. Responsive to the confirmation of delivery, the first trusted node delivers the first symmetric encryption key to the first user device.

Abstract: A tamper detecting component for a quantum communication system is a trusted node, configurable as a first endpoint trusted node, a middle-trusted node and a second endpoint trusted node. The trusted node has a tamper detection module and a secure memory. The tamper detection module deletes critical system parameters responsive to detecting physical tampering. The trusted node, as the first endpoint trusted node, exchanges a quantum key, encrypts data and transmits encrypted data. The trusted node as the middle-trusted node exchanges a quantum key, exchanges another quantum key, decrypts and re-encrypts data and transmits encrypted data. The trusted node as the second endpoint trusted node exchanges a quantum key, and decrypts data.

Abstract: A trusted node, for quantum key distribution, has a quantum key engine, a quantum key controller and a trusted node controller. The quantum key engine exchanges quantum keys. The quantum key controller directs encryption and decryption. The trusted node controller directs the quantum key controller and the quantum key engine, and has no direct access to keys and data protected by the system, including unencrypted quantum keys.

Abstract: A quantum communication system has a plurality of trusted nodes. Each trusted node has a quantum key controller, and a quantum transmitter or a quantum receiver. The trusted nodes are configurable as first and second endpoint trusted nodes and middle-trusted nodes between endpoint trusted nodes. The first endpoint trusted node encrypt data comprising a first key, using a first quantum key. Each middle-trusted node decrypts, using a preceding quantum key, and re-encrypts using a succeeding quantum key. The second endpoint trusted node decrypts using a quantum key, so that the first and second endpoint trusted nodes each have the first key.