Avionics Update Validation via External Message Digest Comparison
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Solution Overview
Problem
Current methods for updating avionics equipment software and databases are insecure against malicious third-party interference and logistically complex due to the need for key distribution and certificate management.
Innovation Solution
A method involving a mobile terminal and an update unit integrated into the aircraft, with a database separate from both, uses cryptographic hash functions to generate and compare message digests, ensuring secure validation of update files through secure access and comparison, either manually or automatically, to prevent unauthorized modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cryptographic hash functions with message digest comparison are used to validate update files, then security against unauthorized modifications is improved, but the system requires secure storage and management of reference message digests within the aircraft
Solution Approach 1:
The reference message digest is extracted from the aircraft's integrity module and stored externally on a secure database accessible by the mobile terminal. This removes the burden of secure storage and management of reference digests from the aircraft system, while maintaining the security validation function.
Solution Approach 2:
A mobile terminal acts as an intermediary between the update source and the aircraft's integrity verification system. It securely accesses the external database to obtain reference message digests and performs the comparison validation, serving as a portable security checkpoint that doesn't require permanent installation in the aircraft.
2Reliability
If electronic signatures with asymmetrical key exchange are used to secure update distribution, then security against malicious interference is improved, but logistical complexity increases due to key distribution and certificate management
Solution Approach 1:
The complex key management infrastructure is extracted and replaced with a simpler cryptographic hash function approach. Instead of managing asymmetrical keys and certificates, the system uses message digest comparison where the reference digest is stored externally and accessed via mobile terminal, eliminating the need for complex key distribution systems.
Solution Approach 2:
The security mechanism changes from asymmetrical key exchange with digital signatures to cryptographic hash function comparison. This parameter change simplifies the mathematical complexity from managing key pairs and certificate validation to computing and comparing hash values, reducing infrastructure requirements while maintaining security.
3Ease of operation
If reference message digests are stored within the aircraft's integrity module, then validation can be performed onboard, but the system becomes vulnerable to penetration and requires recurring updates of reference data
Solution Approach 1:
The reference message digest is taken out from the aircraft's integrity module and stored in an external secure database. This externalization prevents attackers from modifying the reference data within the aircraft system, as the authentic reference is now protected outside the potentially compromised onboard environment.
Solution Approach 2:
The mobile terminal temporarily copies the reference message digest from the secure external database during the validation process. This copying approach allows onboard validation without permanently storing vulnerable reference data in the aircraft, maintaining security while enabling functional validation.
Data Source
AI summary
This method makes it possible to validate an update file of at least one set of computer data of a piece of avionics equipment of an aircraft. The processing method is implemented within a processing system comprising a mobile terminal independent of the aircraft, an update unit integrated into the aircraft, and a database separate from the aircraft and the mobile terminal, and comprises obtaining a computed message digest, the computed message digest resulting from the application, by the update unit, of a cryptographic hash function to the update file, obtaining a reference message digest, the reference message digest being acquired by the mobile terminal by secure access to a database comprising the reference message digest, and processing the update file based on a comparison of the computed message digest with the reference message digest.