Variable Epoch Scheduler for Cryptographic Key Rotation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional secure computer systems are vulnerable to adversaries who can learn the regular intervals of secret and share updates, allowing them to recover the secret with high probability, especially when updates occur at fixed intervals.
Innovation Solution
A Variable Epoch Scheduler (VES) generates schedules for key updates with varying durations, ensuring at least two epochs have different lengths, reducing the likelihood of adversaries recovering the secret without decreasing the average duration of epochs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If regular interval key updates are used, then key refresh rate is improved, but vulnerability to adversary increases
Solution Approach 1:
The patent applies dynamics by transitioning from static, fixed-interval key updates to dynamic, variable-interval updates. The epoch scheduler randomly determines the duration of each epoch (time between key updates), making the update pattern unpredictable to adversaries while maintaining adequate refresh rates. This dynamic adjustment prevents adversaries from predicting when key updates occur, thereby reducing their ability to compromise secrets.
Solution Approach 2:
The patent implements periodic action through structured key updates that occur at regular intervals from the system's perspective, while introducing randomness in the actual timing. The epoch scheduler creates periodic update cycles with variable durations, ensuring that keys are refreshed sufficiently often to maintain security while the randomization prevents predictable patterns that adversaries could exploit.
2Object-affected harmful factors
If variable epoch durations are introduced, then adversary success probability decreases, but scheduling complexity increases
Solution Approach 1:
The epoch scheduler implements self-service by autonomously generating random epoch durations and managing the key update schedule without requiring complex external coordination. The scheduler internally maintains the random timing mechanism and automatically coordinates key updates across all players, eliminating the need for complex inter-player negotiation or external control systems while achieving variable interval updates.
Solution Approach 2:
The patent applies parameter changes by modifying the time parameter of key updates from fixed values to random variables. The epoch scheduler changes the duration parameter of each epoch based on random generation, transforming the update pattern from predictable to unpredictable. This parameter transformation simplifies the scheduling logic while effectively preventing adversary prediction of update timing.
3Device complexity
If fixed epoch duration is used, then system simplicity is maintained, but information leakage to adversary increases
Solution Approach 1:
The patent transforms the static, fixed epoch duration into a dynamic, random variable. The epoch scheduler generates different epoch lengths for different epochs, making the time parameter unpredictable to adversaries. This dynamic approach maintains system simplicity from the implementation perspective while preventing information leakage about update timing patterns to adversaries.
Solution Approach 2:
The patent implements periodic key updates while introducing random variation in the period length. The epoch scheduler creates a rhythmic update pattern that appears regular from the system's internal perspective but is unpredictable to external observers. This periodic action with random intervals prevents adversaries from inferring update timing information while maintaining adequate security refresh rates.
Data Source
AI summary
An improved technique involves protecting a set of resources in a distributed computer system by scheduling epochs for replacing keys that have a variable duration. Along these lines, a Variable Epoch Scheduler (VES) generates schedules of key updates for a set of players in the distributed system such that at least two epochs in the schedules have different durations. For example, the epoch durations within a schedule may vary, or the epoch durations for different players may be different. At the end of each epoch, the VES notifies the distributed system to update the key identified in the schedule as corresponding to that epoch.