Hierarchical Security Key Management for Subscriber Revocation
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Solution Overview
Problem
Managing security keys for anonymous subscribers is challenging, particularly in scenarios where revoking keys from lapsed subscribers requires reconfiguring all other keys, leading to inefficiencies and increased costs for providers.
Innovation Solution
A method for managing security keys that involves monitoring user eligibility and invalidating keys based on economic policies, including cost assessments for providers, and using a structured hierarchy to allocate keys, minimizing the impact of key invalidation on valuable users by grouping them in domains with fewer ancestral keys, thus reducing the need for extensive reconfiguration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each user is issued with a unique key that does not identify the subscriber, then anonymity of subscribers is preserved, but revocation of keys from lapsed subscribers requires reconfiguration of all other subscriber's keys
Solution Approach 1:
The patent segments the key hierarchy into multiple levels (master keys, session keys, user-specific keys) where revocation of a single user's key only requires reconfiguration of that user's specific keys and immediate parent keys, not all keys in the system. This segmentation isolates the impact of key revocation to minimal scope.
Solution Approach 2:
The patent introduces a temporal dimension to key management by implementing key versions and expiration mechanisms. Instead of managing a static set of keys, the system manages keys across time dimensions, allowing selective invalidation of specific key versions without affecting other keys, thus reducing reconfiguration requirements.
2Ease of operation
If a single security key is given to all users, then key management is simplified, but security offered by the single key is compromised
Solution Approach 1:
The patent divides a single master key into multiple derived session keys and user-specific keys through a hierarchical structure. Each user receives a unique derived key from the master key, maintaining simplicity at the top level while providing security differentiation at the user level. Revocation affects only individual user keys, not the master key or other user keys.
Solution Approach 2:
The master key serves multiple functions: it generates all user-specific keys, enables centralized key management, and provides the cryptographic foundation for the entire system. This multi-functionality allows simplified management at the master key level while maintaining security and uniqueness at the user key level.
3Reliability
If keys are invalidated frequently to maintain security, then security of service is improved, but disruption and costs to provider increase
Solution Approach 1:
The patent implements dynamic key management where keys have configurable lifecycles, expiration policies, and revocation conditions. Instead of static key assignment, the system dynamically adjusts key validity based on user status, subscription periods, and security events, allowing optimized balance between security and service continuity.
Solution Approach 2:
The patent changes key parameters such as expiration dates, validity periods, and revocation thresholds to optimize the balance between security and service disruption. By adjusting these parameters, the system can maintain security while minimizing the frequency and impact of key invalidation events on service provision.
Data Source
AI summary
Security keys for the provision of a secure service such as content provision are generated in an ancestral hierarchy, so that invalidation of a key in the hierarchy results in a need to reconfigure all other keys in the hierarchy to the extent they share common ancestry. When a user subscription to the service lapses, a decision on invalidation of their key is based in a determination of whether it's more costly to the subscriber to invalidate the key, or continue providing an unpaid-for service. Keys can be allocated to users from domains of the hierarchy on the basis of their economic value to the provider, with higher value users being allocated keys from domains which share fewer common ancestors with other users of other domains than those users share with each other, to minimise inconvenience to high value users of key reconfiguration.