Signed Permission Object for Secure Diagnostic Access
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Solution Overview
Problem
Existing solutions for conditional access to diagnostic functions in hardware devices, such as set-top boxes, are inadequate as they lack flexibility in managing debugging permissions, do not account for device malfunctions, and pose security risks when unlocking diagnostic features, especially in scenarios where continuous connectivity is not available.
Innovation Solution
A method and system that utilize a signed permission object with an expiration counter to securely unlock diagnostic functions, allowing for flexible management of debugging capabilities and maintaining an audit trail to prevent misuse, by validating and updating the permission object based on device-specific information and sequence numbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a separate hardware configuration is used for test/prototype devices to enable debugging, then debugging functionality is improved, but device complexity increases and production devices cannot be debugged
Solution Approach 1:
The patent implements dynamic configuration where the hardware device can switch between test mode and production mode through a mode indicator. This allows the same physical device to exhibit different functional characteristics - enabling debugging in test mode while maintaining security in production mode, thereby resolving the contradiction between debugging ease and device complexity
Solution Approach 2:
The patent creates a universal device that can serve both as a test/prototype device and a production device. By incorporating a mode indicator and conditional access mechanisms, the same hardware platform performs multiple functions - debugging operations when in test mode and secure production operations when in production mode, eliminating the need for separate hardware configurations
2Reliability
If digital certificates are used to bind code to a specific device for secure debugging, then security is improved, but flexibility and ease of managing debugging permissions deteriorate
Solution Approach 1:
The patent implements dynamic permission management where debugging access is controlled by a mode indicator state rather than static device-bound certificates. The system can dynamically enable or disable debugging functionality based on the current mode, allowing flexible grant and revocation of permissions without requiring new cryptographic bindings, thus resolving the contradiction between security and flexibility
Solution Approach 2:
The patent changes the control parameter from cryptographic device identifiers to a simple mode indicator state. This parameter change allows the system to maintain security through authenticated mode transitions while gaining flexibility in managing debugging permissions through state changes rather than cryptographic operations, resolving the contradiction between reliability and adaptability
3Ease of repair
If diagnostic functions are unlocked in a hardware device for debugging, then ease of repair is improved, but device security deteriorates creating security risks
Solution Approach 1:
The patent implements dynamic security states where the device transitions between locked and unlocked states based on mode indicator validation. Debugging functions are only accessible when the mode indicator authenticates test mode, providing controlled ease of repair while maintaining security through state-dependent access control, resolving the contradiction between ease of repair and device security
Solution Approach 2:
The patent applies preliminary anti-action by requiring mode indicator authentication before enabling debugging functions. This pre-condition prevents unauthorized access to diagnostic features while allowing legitimate debugging when properly authenticated, thus achieving ease of repair for authorized users while maintaining security against unauthorized access
4Ease of operation
If device-bound digital certificates are used without expiration time, then ease of operation is improved, but reliability deteriorates due to inability to expire or invalidate certificates
Solution Approach 1:
The patent implements dynamic access control through a mode indicator that can be changed at any time. Instead of relying on static expiration dates, the system dynamically controls access by switching modes - when the mode indicator changes from test mode to production mode, all debugging permissions are immediately revoked. This provides both operational simplicity and the ability to expire/invalidate access, resolving the contradiction between ease of operation and reliability
Data Source
AI summary
A method and system for unlocking diagnostic functions in a hardware device for a user. The method obtains a signed permission object for the hardware device, and validates the signed permission object. A memory of the hardware device stores a device identifier and a last recorded sequence number. The signed permission object includes a sequence number and is associated with an expiration counter having an initial value that indicates a lifetime for the signed permission object. When the signed permission object is valid, the method updates the expiration counter to decrease the lifetime of the signed permission object, stores the sequence number associated with the signed permission object as the last recorded sequence number in the hardware device, and unlocks the diagnostic functions for the user based on the signed permission object.