Know Thy Neighbor: Cross-TEE Mutual Attestation
2026-07-01 • Cryptography and Security
Cryptography and Security
AI summaryⓘ
The authors explain that cloud services involve many different parts that need to securely communicate, especially when using special secure areas called Trusted Execution Environments (TEEs). Usually, two secure applications (TAs) check each other's security settings using remote attestation. But this gets tricky when the two apps run on different types of TEEs, because each TEE would need to understand the other's security checks. To solve this, the authors created Hema, a new protocol that lets these different TEEs verify each other more easily and safely. They also made sure this protocol is formally verified, meaning its security properties have been mathematically proven.
Cloud servicesTrusted Execution Environment (TEE)Trusted Application (TA)Remote attestationMutual attestationCross-TEE attestationSGXTrustZoneFormal verificationSecurity protocol
Authors
Daniel Andrade, João N. Silva, Miguel P. Correia
Abstract
Cloud services are composed of multiple heterogeneous distributed components and instances that communicate with one another. This occurs both in applications and services running in traditional execution environments and in trusted applications (TAs) running in trusted execution environments (TEEs). TA instances use attestation before exchanging information to ensure all parties meet the expected security conditions. The straightforward solution to mutually attesting two TA instances that are willing to communicate is employing remote attestation mechanisms in both directions. This is typically the case when the two TA instances are running on TEEs of the same type. In order to support cross-TEE attestation, such an approach, that is, using remote attestation in both directions, would require each TEE type (e.g., SGX, TrustZone) to support the attestation software stack of all other TEE types with which it needs to interact. A dedicated cross-TEE mutual attestation solution has multiple benefits in terms of efficiency and security. This paper presents the Heterogeneous Mutual Attestation (Hema) protocol, a formally-verified protocol for the mutual attestation of TA instances running on the same TEE type or on different TEE types.