# US 10,873,455 B2 · Techniques for encryption key rollover synchronization in a network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,455 B2 - Document ID: US10873455B2 - Status: Granted - Kind: B2 - Application number: 16/005,990 - Filed: 2018-06-12 - Published: 2019-09-19 - Granted: 2020-12-22 - Earliest claimed: 2018-03-15 - Assignees: Cisco Technology, Inc. - Applicants: Cisco Technology, Inc. - Inventors: Brian Weis; David M. Carrel; Michael L. Sullenberger - Web page: https://patentgrep.com/patent/US10873455B2 ## CPC - H04L 9/12: Transmitting and receiving encryption devices synchronised or initially set up in a particular manner - H04L 9/0827: {involving distinctive intermediate devices or communication paths (network architectures or network communication protocols using different networks H04L63/18)} - H04L 9/0891: {Revocation or update of secret information, e.g. encryption key update or rekeying} - H04L 63/0442: {wherein the sending and receiving network entities apply asymmetric encryption, i.e. different keys for encryption and decryption (cryptographic mechanisms or cryptographic arrangements for public-key encryption H04L9/30)} - H04L 63/062: {for key distribution, e.g. centrally by trusted party (cryptographic mechanisms or cryptographic arrangements for key distribution involving a central third party H04L9/0819)} - H04L 63/068: {using time-dependent keys, e.g. periodically changing keys (cryptographic mechanisms or cryptographic arrangements for controlling usage of secret information H04L9/088)} - H04L 63/16: {Implementing security features at a particular protocol layer} - H04L 63/164: {at the network layer} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Techniques are presented for encryption key rollover synchronization in a network. In one embodiment, a method includes generating a new set of public-key encryption keys for a first network element. Based on the new set of public-key encryption keys, a set of new security associations between the first network element and each other network element in the network is generated. The method includes providing a new public key from the new set of public-key encryption keys to a network controller and using security associations associated with a previous set of public-key encryption keys for encrypted communication between the first network element and each other network element. Upon obtaining, from a second network element, traffic protected by a security association from the set of new security associations, the method includes using the new security associations for subsequent encrypted communication between the first network element and the second network element. ## Claims ### Claim 1 A method comprising: generating a new set of public key encryption keys for a first network element in a network comprising a plurality of network elements; based on the new set of public-key encryption keys, generating a set of new security associations between the first network element and each other network element of the plurality of network elements in the network; providing a new public key from the new set of public-key encryption keys for the first network element to a network controller in communication with the plurality of network elements; using security associations associated with a previous set of public-key encryption keys to protect traffic for encrypted communication between the first network element and each other network element in the network; and upon obtaining, from a second network element of the plurality of network elements, traffic protected by a security association from the set of new security associations, using security associations from the set of new security associations for subsequent encrypted communication between the first network element and the second network element, wherein the first network element and the second network element exchange peer-to-peer encrypted communication directly without passing through the controller, and only the network controller distributes public key cryptographic material on behalf of the first network element to the second network element. ### Claim 2 (depends on 1) The method of claim 1, further comprising: obtaining from the network controller, at the first network element, a new public key from a new set of public-key encryption keys for one or more network elements of the plurality of network elements; based on the new public key for the one or more network elements, generating another set of new security associations between the first network element and each of the one or more network elements; and using security associations from the another set of new security associations to protect traffic for subsequent encrypted communication between the first network element and each of the one or more network elements. ### Claim 3 (depends on 2) The method of claim 2, further comprising: upon obtaining encrypted communication, at the first network element, from the one or more network elements using a security association from the another set of new security associations, deactivating security associations associated with previous public keys for each of the one or more network elements. ### Claim 4 (depends on 1) The method of claim 1, further comprising: obtaining encrypted communication, at the first network element, from at least one network element of the plurality of network elements, wherein the encrypted communication uses a security association from the set of new security associations; and using security associations from the set of new security associations to protect traffic for subsequent encrypted communication between the first network element and the at least one network element. ### Claim 5 (depends on 4) The method of claim 4, further comprising: deactivating, at the first network element, security associations associated with the previous set of public-key encryption keys for the first network element for subsequent encrypted communication between the first network element and the at least one network element. ### Claim 6 (depends on 4) The method of claim 4, further comprising: setting a timer, at the first network element, upon obtaining the encrypted communication that uses a security association from the set of new security associations; and upon expiration of the timer, deleting the security associations associated with the previous set of public-key encryption keys for the first network element. ### Claim 7 (depends on 1) The method of claim 1, further comprising: obtaining from the network controller, at the first network element, a new public key from a new set of public-key encryption keys for the second network element; and wherein the set of new security associations comprises: a first set of new security associations between the first network element and the second network element based on the new set of public-key encryption keys for the first network element and the new public key for the second network element; and a second set of new security associations between the first network element and the second network element based on the previous set of public-key encryption keys for the first network element and the new public key for the second network element. ### Claim 8 One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor of a first network element in a network comprising a plurality of network elements, cause the processor to: generate a new set of public-key encryption keys for the first network element; based on the new set of public-key encryption keys, generate a set of new security associations between the first network element and each other network element of the plurality of network elements in the network; provide a new public key from the new set of public-key encryption keys for the first network element to a network controller in communication with the plurality of network elements; use security associations associated with a previous set of public-key encryption keys to protect traffic for encrypted communication between the first network element and each other network element in the network; and upon obtaining, from a second network element of the plurality of network elements, traffic protected by a security association from the set of new security associations, use security associations from the set of new security associations for subsequent encrypted communication between the first network element and the second network element, wherein the first network element and the second network element exchange peer-to-peer encrypted communication directly without passing through the controller, and only the network controller distributes public key cryptographic material on behalf of the first network element to the second network element. ### Claim 9 (depends on 8) The one or more non-transitory computer readable storage media of claim 8, further comprising instructions to cause the processor to: obtain from the network controller a new public key from a new set of public-key encryption keys for one or more network elements of the plurality of network elements; based on the new public key for the one or more network elements, generate another set of new security associations between the first network element and each of the one or more network elements; and use security associations from the another set of new security associations to protect traffic for subsequent encrypted communication between the first network element and each of the one or more network elements. ### Claim 10 (depends on 9) The one or more non-transitory computer readable storage media of claim 9, further comprising instructions to cause the processor to: upon obtaining encrypted communication from the one or more network elements using a security association from the another set of new security associations, deactivate security associations associated with previous public keys for each of the one or more network elements. ### Claim 11 (depends on 8) The one or more non-transitory computer readable storage media of claim 8, further comprising instructions to cause the processor to: obtain encrypted communication from at least one network element of the plurality of network elements, wherein the encrypted communication uses a security association from the set of new security associations; and use security associations from the set of new security associations to protect traffic for subsequent encrypted communication between the first network element and the at least one network element. ### Claim 12 (depends on 11) The one or more non-transitory computer readable storage media of claim 11, further comprising instructions to cause the processor to: deactivate security associations associated with the previous set of public-key encryption keys for the first network element for subsequent encrypted communication between the first network element and the at least one network element. ### Claim 13 (depends on 11) The one or more non-transitory computer readable storage media of claim 11, further comprising instructions to cause the processor to: set a timer upon obtaining the encrypted communication that uses a security association from the set of new security associations; and upon expiration of the timer, delete the security associations associated with the previous set of public-key encryption keys for the first network element. ### Claim 14 (depends on 8) The one or more non-transitory computer readable storage media of claim 8, further comprising instructions to cause the processor to: obtain from the network controller a new public key from a new set of public-key encryption keys for the second network element; and wherein the set of new security associations comprises: a first set of new security associations between the first network element and the second network element based on the new set of public-key encryption keys for the first network element and the new public key for the second network element; and a second set of new security associations between the first network element and the second network element based on the previous set of public-key encryption keys for the first network element and the new public key for the second network element. ### Claim 15 An apparatus comprising: at least one network port for communicating in a network; a memory; a processor coupled to the memory and to the at least one network port, wherein the processor is configured to: generate a new set of public-key encryption keys for the apparatus; based on the new set of public-key encryption keys, generate a set of new security associations between the apparatus and each network element of a plurality of network elements in the network; provide a new public key from the new set of public-key encryption keys for the apparatus to a network controller in communication with the plurality of network elements; use security associations associated with a previous set of public-key encryption keys to protect traffic for encrypted communication between the apparatus and each network element of the plurality of network elements; and upon obtaining, from a first network element of the plurality of network elements, traffic protected by a security association from the set of new security associations, use security associations from the set of new security associations for subsequent encrypted communication between the apparatus and the first network element, wherein the first network element and the second network element exchange peer-to-peer encrypted communication directly without passing through the controller, and only the network controller distributes public key cryptographic material on behalf of the first network element to the second network element. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the processor is further configured to: obtain from the network controller a new public key from a new set of public-key encryption keys for one or more network elements of the plurality of network elements; based on the new public key for the one or more network elements, generate another set of new security associations between the apparatus and each of the one or more network elements; and use security associations from the another set of new security associations to protect traffic for subsequent encrypted communication between the apparatus and each of the one or more network elements. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the processor is further configured to: upon obtaining encrypted communication from the one or more network elements using a security association from the another set of new security associations, deactivate security associations associated with previous public keys for each of the one or more network elements. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein the processor is further configured to: obtain encrypted communication from at least one network element of the plurality of network elements, wherein the encrypted communication uses a security association from the set of new security associations; and use security associations from the set of new security associations to protect traffic for subsequent encrypted communication between the apparatus and the at least one network element. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein the processor is further configured to: deactivate security associations associated with the previous set of public-key encryption keys for the apparatus for subsequent encrypted communication between the apparatus and the at least one network element. ### Claim 20 (depends on 18) The apparatus of claim 18, wherein the processor is further configured to: set a timer upon obtaining the encrypted communication that uses a security association from the set of new security associations; and upon expiration of the timer, delete the security associations associated with the previous set of public-key encryption keys for the apparatus.