Enhancing Digital Certificate Usability in Long Lifespan IoT Devices by Utilizing Private CA

Table 5

Comparison between the proposed architecture and the traditional approaches.

Factors	A1	A2	Proposed architecture
Issue cost	High	High	Low
External factors risk	High	High	None
Attack surfaces (number of CAs that can be targeted)	High	High	Low
Risk of failure during certificate update	High	High	Low
Risk of firmware being tampered	High	Low	Low
Management cost (operate, labor cost)	Low	Low	High
CA reliability	High	High	Relatively low
Internal factor risk (insider threats)	Low	Low	Relatively high
Verification time	Slow	Slow	Fast