Offline Online Certificate Authority Segmentation for Secure Issuance
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Solution Overview
Problem
Existing certificate authority systems face challenges in issuing digital certificates online while maintaining security, especially when device characteristics and customer-specific information are unknown at the time of initial offline generation, and when short-lived certificates are required.
Innovation Solution
A system and method that involves an Offline Certificate Authority (OFFCA) generating pre-encoded private keys and certificates, which are then used by an Online Certificate Authority (ONCA) to issue customer-specific digital certificates upon request, ensuring security by limiting the ONCA's capabilities to only sign and not generate or modify private keys, and utilizing pre-generated templates based on customer-specific information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CA is kept in a secure offline facility, then security of private keys is improved, but online certificate issuance capability deteriorates
Solution Approach 1:
The system divides the CA functionality into two separate components: an offline CA that generates and secures private keys, and an online CA that handles certificate issuance requests. This segmentation allows the offline CA to maintain high security by remaining offline, while the online CA provides convenient online certificate issuance without needing to access private keys.
Solution Approach 2:
The patent introduces an intermediary mechanism where the offline CA signs a master certificate that is then used by the online CA to issue certificates. This intermediary approach allows the online CA to function independently without directly accessing the offline CA's private keys, thus maintaining security while enabling online operations.
2Adaptability or versatility
If device characteristics are included in certificates, then customer-specific certification is improved, but key generation complexity increases
Solution Approach 1:
The offline CA performs preliminary actions by generating master private keys and signing master certificates in advance, before any specific device certification is needed. This preliminary setup creates a reusable framework that simplifies subsequent online certificate issuance, as the complex key generation and signing operations are already completed.
Solution Approach 2:
The system uses copying by creating multiple device-specific certificates from a single master certificate template. The online CA can efficiently generate numerous customer-specific certificates by copying and customizing the master certificate structure, rather than generating entirely new key pairs for each device.
3Productivity
If certificates are issued in batches ahead of request, then productivity is improved, but certificate freshness deteriorates
Solution Approach 1:
The offline CA performs preliminary key generation and master certificate signing in advance, creating a pool of cryptographic materials that can be quickly distributed. This preliminary action separates the time-consuming key generation phase from the certificate issuance phase, allowing fast online distribution without compromising security.
Solution Approach 2:
The system extracts the time-consuming key generation operations from the online certificate issuance process. By moving key generation to the offline CA and using pre-generated keys for online certificate signing, the system achieves both high productivity in online issuance and maintains certificate freshness since keys are not reused across different issuance timeframes.
Data Source
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AI summary
In a system comprising an customer providing a service to a plurality of client devices, a method and system for providing an customer-specific digital certificate to a client device of the plurality of client devices is disclosed. The method comprises receiving, in an intermediate certificate authority, a pre-generated digital certificate and an encrypted client device private key encrypted according to a private key encryption key PrKEK, receiving, from the client device, a request for the customer-specific digital certificate, the request comprising at least one of client device identifying information and information identifying the customer, the request signed according to a pre-provisioned client device digital certificate, and transmitting the customer-specific digital certificate and the encrypted client device private key to the client device.