Entitlement management message epoch as an external trusted time source
AssigneeARRIS Enterprises LLC
InventorsAlexander Medvinsky, Douglas M. Petty
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Abstract
An external trusted time source is implemented over a network for conditional access system (CAS)/digital rights management (DRM) client devices. A client device includes untrusted software and a trusted execution environment (TEE) for processing an entitlement management message (EMM) that includes an epoch sequence number (ESN) transmitted from an EMM server using a first network connection. A remaining client key set (CKS) lifetime value is stored and updated in the TEE based on the ESN processed.
Claims18
A method for implementing an external trusted time source over a network to a conditional access system (CAS) client device, the method comprising:
- transmitting an entitlement management message (EMM) to a trusted execution environment (TEE) of the CAS client device from an EMM server using a first network connection, the EMM including an epoch sequence number (ESN);
- generating an updated remaining client key set (CKS) lifetime value in the TEE based on an initial lifetime duration value for the CKS, and the ESN value in the EMM;
- sealing the CKS, the ESN value in the EMM, and the updated remaining CKS lifetime value as unit information;
- and
- delivering the updated remaining CKS lifetime value and ESN value in the EMM from the TEE to untrusted software in the CAS client device.
Dependencies are inferred from the claim text.