Latte: Layered Attestation for Portable Enclaved Applications

Trusted Execution Environment (TEE) has become increasingly popular in privacy-protected cloud computing, and its rapid development has led to the availability of various heterogeneous TEE platforms on cloud servers. To facilitate portable TEE applications on heterogeneous TEE platforms, portable languages or intermediate representations (IRs) with platform-dependent TEE runtimes are adopted. However, existing remote attestation solutions for portable TEE applications follow a nested attestation pattern, i.e., attesting only the TEE runtime and relying on the TEE runtime to measure the loaded portable application, leading to potential security issues. On the other hand, directly packing the TEE runtime and the portable application into an enclave for secure attestation undermines the portability of the portable TEE applications.In this paper, we introduce the concept of portable identities to identify portable TEE applications, and propose a layered attestation framework, Latte, achieving both security and portability in attesting portable TEE applications. We provide a prototype implementation of Latte to validate its practicality, with WebAssembly as the portable IR, and Intel SGX and RISC-V Penglai as the exemplar heterogeneous TEEs. The evaluation demonstrates that Latte introduces minimal performance overhead compared with the nested attestation pattern.