Client Device Authentication Using Group Key Files
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Solution Overview
Problem
Existing authentication methods for client devices in digital content distribution require connection to a central validation authority, leading to inefficiencies and security vulnerabilities, particularly in revoking expired or compromised certificates.
Innovation Solution
The solution employs digital signatures stored in client devices for authentication and key exchange, utilizing group key files with expiration timestamps, allowing for secure authentication and key exchange without central authority connection, and includes a proactive revocation mechanism using regularly updated group key files.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a central validation authority is used to verify digital certificates, then certificate authenticity can be ensured, but authentication time increases and system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-distributing root validation certificates to client devices during manufacturing. These root certificates are stored in the device's secure memory, enabling local validation of digital certificates without requiring real-time connection to a central validation authority. This preliminary setup allows the device to independently verify certificates offline, eliminating authentication delays while maintaining reliability.
2Ease of operation
If digital certificates are stored in client devices for authentication, then authentication convenience is improved, but security risks increase if certificates are compromised
Solution Approach 1:
The patent implements dynamics by making the validation certificate set in client devices updateable. The system allows remote distribution of updated root validation certificates to client devices, enabling the validation authority to revoke or update certificates dynamically. This dynamic capability maintains security by allowing certificate revocation while preserving authentication convenience through continued local validation.
Solution Approach 2:
The patent uses an intermediary approach by introducing a trusted root validation certificate as a mediator between the validation authority and the digital certificates. The root certificate serves as a trusted intermediary that signs validation certificates, which in turn sign content. This hierarchical intermediary structure enhances security by adding layers of verification while maintaining convenience through local validation.
3Reliability
If certificate revocation lists are distributed to local servers, then revoked certificates can be identified, but data management complexity and security vulnerabilities increase
Solution Approach 1:
The patent extracts the revocation mechanism from the complex CRL distribution model and integrates it directly into client devices. Instead of requiring servers to maintain and distribute separate CRL files, the validation authority directly updates root validation certificates in client devices when revocation is needed. This extraction simplifies the system by eliminating the intermediate CRL management layer while maintaining reliable revocation capability.
Data Source
AI summary
A method and system for authorizing client devices to receive secured data streams through the use of digital certificates embedded in the client devices. A freely distributed cryptographically signed group file with an embedded expiration date is associated with each individual digital certificate. A single group file can be associated with more than one digital certificate but each digital certificate is associated with a single group file. The group file contains cryptographic keys that can be used to decrypt a section of the digital certificate revealing a set of client keys. The client keys are then used to encrypt a program key which are then sent back to the client device. When the client device requests a specific data stream or digital content, an issuance timestamp associated with the content is compared to the expiration date in the group file. If the issuance timestamp is after the expiration date, the client device is declined. If the issuance timestamp is before the expiration date, the requested content, encrypted utilizing the program key, is sent to the client device.