In serverless computing, applications are composed of stand-alone microservices that are invoked and scale up independently. Peer-to-peer protocols can be used to enable decentralized communication among the services that compose each application. This paper presents Themis, a framework for secure service-to-service interaction targeting these environments and the underlying service mesh architectures. Themis builds on a notion of decentralized identity management to allow confidential and authenticated service-to-service interaction without the need for a centralized certificate authority. Themis adopts a layered architecture. Its lower layer forms a core communication protocol pair that offers strong security guarantees without depending on a centralized point of authority. Building on this pair, an upper layer provides a series of actions related to communication and identifier management—e.g., store, find, and join. This paper analyzes the security properties of Themis’s protocol suite and shows how it provides a decentralized and flexible communication platform. The evaluation of our Themis prototype targeting serverless applications written in JavaScript shows that these security benefits come with small runtime latency and throughput overheads, and modest startup overheads.

The number of applications and services that are hosted on cloud platforms is constantly increasing. Nowadays, more and more applications are hosted as services on cloud platforms, co-existing with other services in a mutually untrusted environment. Facilities such as virtual machines, containers and encrypted communication channels aim to offer isolation between the various applications and protect sensitive user data. However, such techniques are not always able to provide a secure execution environment for sensitive applications nor they offer guarantees that data are not monitored by an honest but curious provider once they reach the cloud infrastructure. The recent advancements of trusted execution environments within commodity processors, such as Intel SGX, provide a secure reverse sandbox, where code and data are isolated even from the underlying operating system. Moreover, Intel SGX provides a remote attestation mechanism, allowing the communicating parties to verify their identity as well as prove that code is executed on hardware-assisted software enclaves. Many approaches try to ensure code and data integrity, as well as enforce channel encryption schemes such as TLS, however, these techniques are not enough to achieve complete isolation and secure communications without hardware assistance or are not efficient in terms of performance. In this work, we design and implement a practical attestation system that allows the service provider to offer a seamless attestation service between the hosted applications and the end clients. Furthermore, we implement a novel caching system that is capable to eliminate the latencies introduced by the remote attestation process. Our approach allows the parties to attest one another before each communication attempt, with improved performance when compared to a standard TLS handshake.