Time Acquisition for Clockless Devices Using Network Sources
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Solution Overview
Problem
Devices without independent clocks, such as smart cards, cannot accurately enforce time-based security policies or participate in transactions requiring reliable time measurements, as they lack the ability to maintain an internal clock.
Innovation Solution
A method to acquire time from network-attached time sources and estimate the current time, along with a reliability index, to enforce time-based transaction policies, using techniques like TLS connections with dedicated time-servers, symmetric keys, and general-purpose time-servers, ensuring secure and accurate time measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a device does not have an independent clock, then the device can be simpler and consume less power, but the device cannot enforce time-based security policies or participate in time-dependent transactions
Solution Approach 1:
The patent introduces an intermediary component (time synchronization module) that mediates between the device without a clock and external time sources. This module acquires time from network-attached time sources, estimates current time, and provides time information to applications, allowing the device to enforce time-based security policies without having an independent clock.
2Measurement precision
If a device acquires time from network-attached time sources, then the device can obtain accurate time measurements, but the device requires additional communication infrastructure and security protocols
Solution Approach 1:
The patent implements preliminary actions by establishing secure communication channels and authentication mechanisms before time acquisition. The device sets up TLS connections with dedicated time-servers and configures symmetric keys in advance, ensuring that when time is needed, the communication infrastructure is already in place and authenticated.
3Reliability
If a device uses TLS connections with dedicated time-servers, then the device can ensure secure time acquisition, but the device requires additional security configuration and key management
Solution Approach 1:
The patent implements self-service mechanisms where the device automatically manages security configurations. The time synchronization module handles TLS connection establishment, certificate verification, and key management automatically without requiring manual security configuration by users, thus maintaining high security while improving ease of operation.
4Measurement precision
If a device estimates current time from multiple time sources, then the device can improve time accuracy, but the device requires processing multiple time measurements and calculating reliability indices
Solution Approach 1:
The patent implements feedback mechanisms by continuously monitoring time measurements from multiple sources and adjusting the estimated current time based on reliability indices. The system compares time measurements, evaluates source reliability, and dynamically adjusts the time estimate, creating a feedback loop that improves accuracy while managing processing complexity through systematic evaluation criteria.
Data Source
AI summary
A system and a method for operating a device that is not capable of independently maintaining a local time clock to enforce a time-based transaction policy that requires a reliable time reference. The device establishes a secure communications channel to one or more network-attached time sources and inquires of each of the network-attached time-sources as to the current time using the secure communications channel. The device receives the current time from the network-attached time-sources and uses the received current times to estimate a current calendar time and to compute a reliability index associated with the estimated current calendar time. The device uses the estimated current calendar time and reliability index to enforce the time-based transaction policy.