# US 2019/0174308 A1 · Architecture for Reconfigurable Quantum Key Distribution Networks Based on Entangled Photons Directed by a Wavelength Selective Switch

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- Number: US 2019/0174308 A1
- Document ID: US20190174308A1
- Status: Published application
- Kind: A1
- Application number: 16/250,177
- Filed: 2019-01-17
- Published: 2019-06-06
- Earliest claimed: 2008-01-15
- Assignees: AT&T Intellectual Property II, L.P.
- Applicants: AT&T Intellectual Property II, L.P.
- Inventors: Mikhail Brodsky; Mark David Feuer
- Web page: https://patentgrep.com/patent/US20190174308A1

## CPC

- H04W 12/04: Key management, e.g. using generic bootstrapping architecture [GBA]
- H04B 10/25891: {Transmission components (H04B10/40 takes precedence)}
- H04B 10/70: Photonic quantum communication
- H04J 14/0283: {WDM ring architectures}
- H04L 9/0833: {involving conference or group key (network architectures or network communication protocols for key management in group communication in a packet data network H04L63/065)}
- H04L 9/0852: {Quantum cryptography (transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03)}
- H04L 9/0855: {involving additional nodes, e.g. quantum relays, repeaters, intermediate nodes or remote nodes}
- H04L 9/0858: {Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding}
- H04L 9/30: Public key, i.e. encryption algorithm being computationally infeasible to invert or user's encryption keys not requiring secrecy
- H04L 2209/24: Key scheduling, i.e. generating round keys or sub-keys for block encryption
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A system and method for securing communications between a plurality of users communicating over an optical network. The system utilizes a fixed or tunable source optical generator to generate entangled photon pairs, distribute the photons and establish a key exchange between users. The distribution of entangled photon pairs is implemented via at least one wavelength selective switch.

## Claims

### Claim 1

A method for encrypting messages sent between a number of endpoints, the number of endpoints comprising a plurality of sender devices and a plurality of recipient devices, the method comprising:
receiving a plurality of encryption photons at a first sender device of the plurality of sender devices beginning at a scheduled connection time and continuing during a scheduled duration period, each encryption photon of the plurality of encryption photons comprising one entangled photon of a pair of entangled photons, the scheduled connection time and the scheduled duration period allowing the number of endpoints to receive a plurality of photons when the number of endpoints exceeds a number of wavelength channels for transmission of the plurality of photons;
generating an encryption key at the first sender device of the plurality of sender devices based on the plurality of encryption photons; and
encrypting an electronic message using the encryption key.

### Claim 2 (depends on 1)

The method of claim 1, wherein the pair of entangled photons has a known frequency relationship.

### Claim 3 (depends on 2)

The method of claim 2, wherein each of the plurality of encryption photons has one of a vertical polarization and a horizontal polarization.

### Claim 4 (depends on 3)

The method of claim 3, wherein the generating the encryption key is based on a polarization of each encryption photon of the plurality of encryption photons.

### Claim 5 (depends on 1)

The method of claim 1, wherein the encrypting the electronic message generates an encrypted electronic message, the method further comprising:
transmitting the encrypted electronic message to a first recipient device of the plurality of recipient devices,
wherein a decryption key generated by the first recipient device of the plurality of recipient devices is based on a plurality of decryption photons received by the first recipient device of the plurality of recipient devices, the plurality of decryption photons associated with the plurality of encryption photons.

### Claim 6 (depends on 1)

The method of claim 1, wherein the plurality of encryption photons are from a source separate from the first sender device of the plurality of sender devices and a first recipient device of the plurality of recipient devices.

### Claim 7 (depends on 1)

The method of claim 1, wherein the encrypting the electronic message generates an encrypted electronic message capable of decryption using a decryption key generated at a first recipient device of the plurality of recipient devices based on a plurality of decryption photons, each decryption photon of the plurality of decryption photons comprising a respective other entangled photon of the pair of entangled photons transmitted to the first recipient device beginning at the scheduled connection time and continuing during the scheduled duration period.

### Claim 8 (depends on 1)

The method of claim 1, wherein the pair of entangled photons is generated by degenerate four-wave mixing.

### Claim 9 (depends on 1)

The method of claim 1, wherein the pair of entangled photons is generated by parametric down-conversion.

### Claim 10 (depends on 1)

The method of claim 1, wherein the pair of entangled photons is centered at an optical source frequency.

### Claim 11

A method for decrypting messages sent between a number of endpoints, the number of endpoints comprising a plurality of sender devices and a plurality of recipient devices, the method comprising:
receiving a plurality of decryption photons at a first recipient device of the plurality of recipient devices beginning at a scheduled connection time and continuing during a scheduled duration period, each decryption photon of the plurality of decryption photons comprising one entangled photon of a pair of entangled photons, the scheduled connection time and the scheduled duration period allowing the number of endpoints to receive a plurality of photons when the number of endpoints exceeds a number of wavelength channels for transmission of the plurality of photons;
generating a decryption key at the first recipient device of the plurality of recipient devices based on the plurality of decryption photons; and
decrypting an encrypted electronic message using the decryption key.

### Claim 12 (depends on 11)

The method of claim 11, wherein the pair of entangled photons has a known frequency relationship.

### Claim 13 (depends on 12)

The method of claim 12, wherein each of the plurality of decryption photons has one of a vertical polarization and a horizontal polarization.

### Claim 14 (depends on 13)

The method of claim 13, wherein the generating the decryption key is based on a polarization of each decryption photon of the plurality of decryption photons.

### Claim 15 (depends on 11)

The method of claim 11, further comprising:
receiving the encrypted electronic message from a first sender device of the plurality of sender devices,
wherein an encryption key generated by the first sender device of the plurality of sender devices is based on a plurality of encryption photons received by the first sender device of the plurality of sender devices, the plurality of encryption photons associated with the plurality of decryption photons.

### Claim 16 (depends on 11)

The method of claim 11, wherein the plurality of decryption photons are from a source separate from a first sender device of the plurality of sender devices and the first recipient device of the plurality of recipient devices.

### Claim 17 (depends on 11)

The method of claim 11, wherein the encrypted electronic message is encrypted at a first sender device of the plurality of sender devices using an encryption key generated based on a plurality of encryption photons, each encryption photon of the plurality of encryption photons comprising a respective other entangled photon of the pair of entangled photons transmitted to the first sender device of the plurality of sender devices beginning at the scheduled connection time and continuing during the scheduled duration period.

### Claim 18 (depends on 11)

The method of claim 11, wherein the pair of entangled photons is generated by degenerate four-wave mixing.

### Claim 19 (depends on 11)

The method of claim 11, wherein the pair of entangled photons is generated by parametric down-conversion.

### Claim 20 (depends on 11)

The method of claim 11, wherein the pair of entangled photons is centered at an optical source frequency.