CA Certificate Update Mechanism for Resource-Constrained Devices
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Solution Overview
Problem
Existing communication apparatuses with limited resources, such as home appliances, face challenges in verifying server validity and renewing CA certificates due to insufficient memory and lack of clock or timer functionality, making it difficult to manage multiple CA certificates and maintain secure communication.
Innovation Solution
A communication apparatus with a first storage unit for holding CA information, including a first CA certificate and an update address for a download server, and an authentication unit that uses the first CA certificate to verify server validity, with a CA information update unit that periodically or upon revocation, retrieves and updates to a second CA certificate from the download server, eliminating the need for pre-storing multiple CA certificates and managing validity periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple CA certificates are pre-stored in the communication apparatus to ensure continuous authentication capability, then the reliability of server verification is improved, but the memory resource consumption increases significantly
Solution Approach 1:
The system pre-stores only the current valid CA certificate and the URL of the download server before communication begins. When certificate renewal is needed, the apparatus automatically downloads the new CA certificate from the predetermined URL without requiring pre-storage of multiple certificates. This preliminary setup reduces memory usage while ensuring continuous authentication capability.
Solution Approach 2:
The communication apparatus performs self-service by automatically detecting when the current CA certificate expires or is revoked, then autonomously downloading the new CA certificate from the stored URL and updating its authentication credentials. This eliminates the need for manual intervention or pre-storage of backup certificates, reducing memory requirements while maintaining reliability.
2Reliability
If the communication apparatus continuously monitors CA certificate validity periods to ensure timely renewal, then the reliability of authentication is improved, but the device complexity increases due to requirement of clock or timer functionality
Solution Approach 1:
The system uses feedback from the authentication process itself to trigger certificate renewal. When server verification fails or the apparatus attempts to communicate and detects certificate expiration, it automatically initiates download of the new CA certificate from the stored URL. This feedback-based approach eliminates the need for continuous monitoring via clocks or timers, reducing device complexity while maintaining authentication reliability.
3Reliability
If the communication apparatus attempts to download new CA certificate frequently to ensure availability, then the reliability of certificate renewal is improved, but the use of energy and network resources increases
Solution Approach 1:
The communication apparatus performs periodic attempts to download the new CA certificate from the stored URL, rather than continuous monitoring or frequent unnecessary downloads. The system tries to access the download server at appropriate intervals, and only when the download succeeds does it update the CA certificate. This periodic approach ensures reliable certificate renewal while minimizing energy consumption and network resource usage by avoiding redundant download attempts.
Data Source
AI summary
A communication apparatus with a memory (418) holding CA information A(301a) including (i) a CA certificate A(106a) indicating that an AP server certificate A(402a) (that indicates the validity of an application server (401)) is valid and (ii) a URL B(302b) indicating the URL of a download server B(406b) where CA information B(301b) including the next valid CA certificate B(106b) is stored. The communication apparatus also having a server authentication unit (416) verifying the AP server certificate A(402a) using the CA certificate A(106a), and having a CA information update unit (417) obtaining the CA information B(301b) from the download server B(406b) indicated by the URL B(302b), wherein, when the CA certificate A(106a) becomes revoked, the server authentication unit (416) authenticates the application server (401) using the CA certificate B(106b) included in the CA information B(301b) obtained by the CA information update unit (417).