Patent ID: 7697687

Claim:
A method for providing bit-level synchronization and secure resynchronization between a transmitter and a receiver capable of transmitting encrypted data between transmitting and receiving locations, comprising: transmitting a control data from the transmitter to the receiver; transmitting an initiation signal from the transmitter to the receiver during an initialization procedure; enabling a key generator of the transmitter to generate a first running key for use in quantum encryption, the encryption applying an encryption protocol which uses quantum noise to make neighboring M-ary transmission states indistinguishable to an eavesdropper; using the first running key to encrypt the data at the transmitter and transmitting the quantum encrypted data to the receiver over a communication link; the quantum encrypted data implements a physical layer encryption protocol that uses a multilevel signal scheme, wherein the multilevel signal is determined by the binary data and a running key; applying a transmitted data, including the initiation signal to a clock recovery circuit of the receiver to produce a local clock for the receiver; enabling a key generator of the receiver to generate a second running key at the receiver, the second running key being the same as the first running key; using the second running key to decrypt the encrypted data at the receiver; using the initialization signal to synchronize a start of quantum encryption with a start of decryption; and transmitting a synchronization signal from the receiver to the transmitter over a control channel to start the resynchronization procedure when synchronization is lost.