Be it in the IoT or automotive domain, implicit certificates are gaining ever more prominence in constrained embedded devices. They present a resource-efficient security solution against common threat concerns. The computational requirements are not the main issue anymore. The focus is now placed on determining a good balance between the provided security level and the derived threat model. A security aspect that often gets overlooked is the establishment of secure communication sessions, as most design solutions are based only on the use of static key derivation, and therefore, lack the perfect forward secrecy. This leaves the transmitted data open for potential future exposures by having keys tied to the certificates rather than the communication sessions. We aim to patch this gap, by presenting a design that utilizes the Station to Station (STS) protocol with implicit certificates. In addition, we propose potential protocol optimization implementation steps and run a comprehensive study on the performance and security level between the proposed design and the state-of-the-art key derivation protocols. In our comparative study, we show that with a slight computational increase of 20\% compared to a static ECDSA key derivation, we are able to mitigate many session-related security vulnerabilities that would otherwise remain open.

翻译：无论是在物联网还是汽车领域，隐式证书在受限嵌入式设备中日益受到重视。它们为应对常见威胁提供了一种资源高效的安全解决方案。计算需求已不再是主要问题，当前焦点转向在所提供的安全级别与衍生威胁模型之间寻求良好平衡。一个常被忽视的安全问题在于安全通信会话的建立——由于大多数设计方案仅基于静态密钥推导，因此缺乏完美前向保密性。这导致传输数据因密钥与证书而非通信会话绑定，未来可能面临泄露风险。为弥补这一缺口，我们提出一种利用站间协议（STS）结合隐式证书的设计方案。此外，我们提出了潜在的协议优化实现步骤，并在所提设计与现有最优密钥推导协议之间开展了性能与安全级别的综合研究。对比研究表明，与静态ECDSA密钥推导相比，仅增加20%的计算开销即可消除许多原本存在的会话相关安全漏洞。