Time-Dependent Credentials for Distributed System Authentication
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Solution Overview
Problem
In distributed computer systems, the challenge of maintaining consistent credentials across multiple instances of a service is exacerbated by differences in local timekeeping among controllers, leading to inconsistencies and potential authentication failures during credential transitions.
Innovation Solution
The system generates and uses time-dependent credentials, including a first credential for the current interval and a second credential for the preceding interval, along with an indication of whether the credential was generated within a transition window, allowing devices to selectively use appropriate credentials to ensure consistent authentication functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If credentials are periodically updated across multiple distributed devices, then security is improved, but authentication failures and service disruptions occur due to time synchronization issues
Solution Approach 1:
The system performs preliminary credential updates on a subset of devices before system-wide deployment. Controllers are updated in waves, with each wave updating a portion of controllers ahead of time, allowing the system to prepare for credential transitions without causing widespread authentication failures.
Solution Approach 2:
The system dynamically adjusts credential validity periods and transition windows based on system state. During transition periods, the authentication system accepts both old and new credentials, dynamically expanding the acceptance window to prevent authentication failures while credentials are being updated across the distributed system.
2Reliability
If manual credential updates are performed, then credential secrecy is maintained, but operational complexity and personnel costs increase
Solution Approach 1:
Controllers automatically perform credential updates without requiring manual intervention. The system implements self-service credential management where controllers autonomously generate, store, and update credentials based on configured policies, eliminating the need for personnel to manually update credentials while maintaining security through automated secure key generation and rotation.
Solution Approach 2:
The system pre-configures credential update policies, validity periods, and transition parameters before deployment. This preliminary configuration establishes automated update schedules and security parameters, allowing the system to execute secure credential rotations automatically without requiring complex real-time decision-making or manual intervention during updates.
3Reliability
If credentials are updated simultaneously across all devices, then credential consistency is improved, but service disruptions increase due to synchronized transitions
Solution Approach 1:
The system segments the credential update process into multiple waves or batches affecting different subsets of controllers at different times. This segmentation prevents simultaneous system-wide transitions, allowing the system to maintain credential consistency within each segment while avoiding widespread service disruptions that would occur with synchronized updates across all devices.
Solution Approach 2:
The system dynamically adjusts credential validity periods and transition windows based on system state and load conditions. During transition periods, the authentication system accepts both old and new credentials, dynamically expanding the acceptance window to prevent authentication failures while credentials are being updated across the distributed system.
4Adaptability or versatility
If different controllers use different local times, then autonomous operation is improved, but credential generation consistency deteriorates
Solution Approach 1:
The system pre-configures credential update policies, validity periods, and transition parameters before deployment. This preliminary configuration establishes automated update schedules and security parameters, allowing the system to execute secure credential rotations automatically without requiring complex real-time decision-making or manual intervention during updates.
Solution Approach 2:
The system dynamically adjusts credential validity periods and transition windows based on system state. During transition periods, the authentication system accepts both old and new credentials, dynamically expanding the acceptance window to prevent authentication failures while credentials are being updated across the distributed system.
Data Source
AI summary
A distributed system in which time-dependent credentials are supplied by controllers that operate according to different local times. Errors that might arise from the controllers generating inconsistent credentials because of time skew are avoided by identifying credentials generated during transition intervals in which different ones of the controllers may generate different credentials at the same absolute time. During a transition interval, controllers and other devices may use credentials differentially based on the nature of the authentication function. Each controller may periodically renew its credentials based on self-scheduled renewals or based on requests from other devices, such that renewal times are offset by random delays to avoid excessive network traffic. Controllers may determine which credential is valid for any given time, based on a cryptographically secure key associated with that time and information identifying the entity that is associated with that credential.