IoT Device Local Authorization via Time-Limited Key Hash Tokens
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Solution Overview
Problem
IoT devices often face challenges in maintaining continuous operation without a network connection, as existing authorization systems require constant connectivity for subscription-based models, and are vulnerable to replay attacks.
Innovation Solution
The system employs a shared secret key-based authorization process with periodic reauthorization, using a timestamp in the key hash to prevent replay attacks and allowing IoT devices to operate in remote locations with minimal network connectivity through an intermediary device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If IoT devices require constant network connectivity for authorization, then subscription-based service models can be maintained, but devices cannot operate in remote locations with no or minimal network connectivity
Solution Approach 1:
The system performs authorization actions in advance by providing a time-limited authorization token that allows the device to operate without continuous network connection. The token is obtained before the device needs to operate in remote location, and remains valid for a predetermined time period, enabling the device to function autonomously during that period.
Solution Approach 2:
The authorization token acts as an intermediary that mediates between the authorization server and the IoT device. Instead of requiring direct continuous communication between the device and server, the token serves as a standalone credential that validates device operations locally without needing real-time server verification.
2Reliability
If traditional authorization systems are used, then devices can maintain continuous authorization status, but they become vulnerable to replay attacks
Solution Approach 1:
The authorization token incorporates a time validity period, requiring periodic reauthorization. Each token is valid only for a predetermined time period and must be renewed by contacting the authorization server again, preventing attackers from indefinitely replaying captured authorization signals.
Solution Approach 2:
The authorization token changes its validity parameters over time by incorporating a predetermined expiration time. This temporal parameter change ensures that authorization credentials become obsolete after a specific duration, fundamentally preventing replay attacks that rely on static, reusable credentials.
3Reliability
If IoT devices perform periodic reauthorization, then authorization freshness is maintained, but additional network communications are required
Solution Approach 1:
The system implements periodic reauthorization where devices contact the authorization server at predetermined intervals to renew their tokens. This periodic approach balances security requirements with energy efficiency, as devices only need to communicate when necessary for renewal rather than continuously or at every operation.
Data Source
AI summary
Systems, devices, and techniques for service authorization are described. A described device includes a transceiver to communicate with an authorization server, and a processor. The processor can set an authorization timer for a first time period based on obtaining an authorization from the authorization server, and activate device features for a duration of the first time period. The processor can receive from the authorization server an authorization message that includes an authorization key hash based on a shared secret key and a server timestamp, determine a local key hash based on the shared secret key and a local timestamp, set the authorization timer for a second time period based on the authorization key hash matching the local key hash, and maintain an activation of the features for a duration of the second time period.