Centralized Certificate Revocation With Offline Key Protection
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Solution Overview
Problem
Existing systems lack a centralized management solution for the full lifecycle of digital certificates, including revocation and rekeying services, especially when devices require online issuance with device-specific information and short certificate lifetimes, posing security risks due to the need for online Certificate Authorities (CAs) that handle device private keys.
Innovation Solution
A system where a centralized Certificate Authority (CCA) manages the full lifecycle of digital certificates, utilizing an Offline Certificate Authority (OFFCA) to generate and encrypt private keys, and an Online Certificate Authority (ONCA) to issue certificates with device-specific information, while ensuring the ONCA cannot decrypt or modify device private keys, using a proxy agent for secure communication and a centralized database for certificate management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an online Certificate Authority is used to issue certificates with device-specific information, then certificate issuance flexibility and speed are improved, but security risk increases due to potential exposure of private keys
Solution Approach 1:
The system segments the CA functionality into two distinct components: an offline CA that generates and securely stores private keys, and an online CA that handles certificate issuance requests. This segmentation allows the online CA to operate without accessing private keys, thus maintaining security while providing fast online certificate issuance capabilities.
Solution Approach 2:
The private key generation and storage functionality is extracted from the online CA and placed in an offline CA system. The online CA only handles certificate signing requests and issuance, while the offline CA securely manages the private keys. This extraction eliminates the security vulnerability of storing private keys in an online system while preserving online certificate issuance capabilities.
2Reliability
If certificates are issued offline in advance, then security is improved by keeping the CA offline, but certificate freshness and availability deteriorate causing delays
Solution Approach 1:
The system divides CA operations into offline key management and online certificate issuance. The offline CA generates keys and signs certificate templates, while the online CA receives requests, validates them, and issues certificates immediately. This segmentation enables both strong offline security and rapid online response.
Solution Approach 2:
The offline CA performs preliminary actions by generating key pairs and signing certificate templates in advance. These pre-signed templates are stored securely and can be quickly instantiated by the online CA when a certificate is needed, enabling fast issuance without compromising the offline security of key generation.
3Reliability
If a centralized Certificate Authority manages all certificate operations, then security control is improved, but system complexity and operational efficiency deteriorate
Solution Approach 1:
The centralized CA system is segmented into an offline CA component for secure key management and an online CA component for certificate issuance operations. This segmentation allows each component to be optimized for its specific function, reducing operational complexity while maintaining centralized security control.
Solution Approach 2:
The system introduces an intermediary mechanism where the offline CA signs certificate templates and the online CA completes the certificate issuance process. This intermediary approach allows centralized security control through the offline CA's digital signatures while distributing operational complexity to the online CA that handles routine issuance requests.
4Adaptability or versatility
If the online CA has full access to private keys for certificate management, then certificate lifecycle management capability is improved, but security risk increases
Solution Approach 1:
Private key access is extracted from the online CA and confined to the offline CA system. The online CA manages certificate lifecycle operations by validating requests, signing certificates with its own key, and coordinating with the offline CA when private key operations are needed. This extraction maintains full certificate lifecycle management capability while eliminating private key exposure risk in the online system.
Solution Approach 2:
The offline CA acts as an intermediary that the online CA consults for private key operations. The online CA handles most certificate lifecycle management independently, and only contacts the offline CA when private key signing or generation is required. This intermediary relationship enables versatile certificate management while maintaining strict security boundaries around private keys.
Data Source
AI summary
A method and apparatus for revoking and replacing digital certificates issued by distributed servers is disclosed. An architecture in which issued certificates from distributed factory and field provisioning servers are gathered into a centrally managed certificate authority which manages the full certificate lifecycle. Revocation and rekey approvals are performed through this central certificate authority, while the resulting revocation status and rekey approvals are made available for consumption by those same distributed servers.