Encryption Key for Inter-Network Communications

1 . A method comprising:

receiving, by a first host device in a first network of a plurality of networks and from an intermediate client device, a request to enroll the intermediate client device into the first network;

determining, by the first host device, whether any other intermediate client device is already enrolled in the first network;

determining, by the first host device and based at least in part on the determination of whether any other intermediate client device is already enrolled in the first network, an inter-network encryption key of the first host device for encrypting communications between the plurality of networks; and

sending, by the first host device in the first network to a second host device in a second network of the plurality of networks, an encrypted message that is encrypted using the inter-network encryption key of the first host device.

2 . The method of claim 1 , wherein:

receiving the request to enroll the intermediate client device into the first network further includes receiving, by the first host device and from the intermediate client device, a candidate inter-network encryption key; and

determining the inter-network encryption key of the first host device further includes in response to determining that no other intermediate client device is already enrolled in the first network, setting, by the first host device, the candidate inter-network encryption key as the inter-network encryption key of the first host device for encrypting communications between the plurality of networks.

3 . The method of claim 1 , further comprising:

after enrolling the intermediate client device into the first network, receiving, by the first host device from a second intermediate client device, a request to enroll the second intermediate client device into the first network;

in response to receiving the request to enroll the second intermediate client device into the first network, determining, by the first host device in the first network, that the intermediate client device is already enrolled into the first network; and

in response to determining that intermediate client device is already enrolled into the first network, sending, by the first host device to the second intermediate client device, the inter-network encryption key of the first host device for encrypting communications between the plurality of networks.

4 . The method of claim 3 , further comprising:

in response to receiving the request to enroll the second intermediate client device into the first network, sending, by the first host device to the second intermediate client device, a security key for the host device,

wherein sending, to the second intermediate client device, the inter-network encryption key of the first host device further comprises:

encrypting, by the host device and using the security key of the host device, the inter-network encryption key to generate an encrypted inter-network encryption key of the first host device, and

sending, by the first host device to the second intermediate client device, the encrypted inter-network encryption key of the first host device.

5 . The method of claim 1 , wherein each of the plurality of networks is provided by a corresponding control device of a building control unit.

6 . The method of claim 5 , wherein:

the first host device is connected to the first network provided by a first control device of a first heating, ventilation, and air conditioning (HVAC) unit; and

the second host device is connected to the second network provided by a second control device of a second HVAC unit.

7 . The method of claim 1 , wherein the intermediate client device comprises one of: a temperature sensor, an outdoor sensor, a humidity sensor, an occupancy sensor, a light sensor, a current sensor, or a smoke sensor.

8 . A host device comprising:

communication circuitry configured to connect to a first network of a plurality of networks;

memory,

processing circuitry operably coupled to the memory and communication circuitry and configured to:

receive, from an intermediate client device via the communication circuitry, a request to enroll the intermediate client device into the first network;

determine whether any other intermediate client device is already enrolled in the first network;

determine, based at least in part on the determination of whether any other intermediate client device is already enrolled in the first network, an inter-network encryption key of the host device for encrypting communications between the plurality of networks; and

send, to the intermediate client device via the communication circuitry, an encrypted message that is encrypted using the inter-network encryption key of the host device for forwarding to a second host device in a second network of the plurality of networks.

9 . The host device of claim 8 , wherein:

to receive the request to enroll the intermediate client device into the first network, the processing circuitry is further configured to receive, from the intermediate client device, a candidate inter-network encryption key; and

to determine the inter-network encryption key of the first host device, the processing circuitry is further configured to, in response to determining that no other intermediate client device is already enrolled in the first network, set the candidate inter-network encryption key as the inter-network encryption key of the first host device for encrypting communications between the plurality of networks.

10 . The host device of claim 8 , wherein the processing circuitry is further configured to:

after enrolling the intermediate client device into the first network, receive, from a second intermediate client device via the communication circuitry, a request to enroll the second intermediate client device into the first network;

in response to receiving the request to enroll the second intermediate client device into the first network, determine that the intermediate client device is already enrolled into the first network; and

in response to determining that intermediate client device is already enrolled into the first network, send, to the second intermediate client device via the communication circuitry, the inter-network encryption key of the host device for encrypting communications between the plurality of networks to enable the second intermediate client device.

11 . The host device of claim 10 , wherein:

the processing circuitry is further configured to:

in response to receiving the request to enroll the second intermediate client device into the first network, send, to the second intermediate client device, a security key for the host device,

wherein to send, to the second intermediate client device, the inter-network encryption key of the first host device, the processing circuitry is further configured to:

encrypt, using the security key of the host device, the inter-network encryption key to generate an encrypted inter-network encryption key of the first host device, and

send, to the second intermediate client device, the encrypted inter-network encryption key of the first host device.

12 . The host device of claim 8 , wherein each of the plurality of networks is provided by a corresponding control device of a building control unit.

13 . The host device of claim 12 , wherein:

the host device is connected to the first network provided by a first control device of a first heating, ventilation, and air conditioning (HVAC) unit; and

the second host device is connected to the second network provided by a second control device of a second HVAC unit.

14 . The host device of claim 8 , wherein the intermediate client device comprises one of: a temperature sensor, an outdoor sensor, a humidity sensor, an occupancy sensor, a light sensor, a current sensor, or a smoke sensor.

15 . A method comprising:

enrolling, by an intermediate client device, in a first network of a plurality of networks;

in response to enrolling in the intermediate client device, receiving, by the intermediate client device from a first host device of the first network, a first inter-network encryption key for encrypting communications between the plurality of networks;

enrolling, by the intermediate client device, in a second network of the plurality of networks;

in response to enrolling in the second network, receiving, by the intermediate client device from a second host device of the second network, a second inter-network encryption key for encrypting communications between the plurality of networks; and

in response to determining that the first inter-network encryption key does not match the second inter-network encryption key, broadcasting, by the intermediate client device across the plurality of networks, the second inter-network encryption key for encrypting communications between the plurality of networks.

16 . The method of claim 15 , wherein broadcasting the second inter-network encryption key further includes:

encrypting, by the intermediate client device using the first inter-network encryption key, the second inter-network encryption key to generate an encrypted second inter-network encryption key; and

broadcasting, by the intermediate client device across the plurality of networks, the encrypted second inter-network encryption key.

17 . The method of claim 15 , wherein receiving the first inter-network encryption key for encrypting communications between the plurality of networks further comprises:

receiving, by the intermediate client device and from the first host device, a security key of the first network;

receiving, by the intermediate client device and from the first host device, an encrypted first inter-network encryption key; and

decrypting, by the intermediate client device and using the security key of the first network, the encrypted first inter-network encryption key to generate the first inter-network encryption key.

18 . The method of claim 15 , wherein the plurality of networks comprise a plurality of wireless networks.

19 . The method of claim 15 , wherein the intermediate client device comprises one of: a temperature sensor, an outdoor sensor, a humidity sensor, a humidity sensor, an occupancy sensor, a light sensor, a current sensor, or a smoke sensor.

20 . The method of claim 15 , wherein the intermediate client device comprises an internet gateway device for connecting the first network and the second network to the Internet.