TEE-assisted Computation Over Ciphertext: A Review

Trusted Execution Environments (TEEs) provide an efficient foundation for ciphertext computation through hardware-enforced isolated execution, enabling secure multi-party data processing. Integrating TEEs with cryptographic techniques allows sensitive data to be processed without exposing the plaintext, thereby supporting collaborative computation in untrusted environments. These lightweight and efficient security mechanisms have driven widespread interest and research into TEE-based ciphertext computation schemes. However, existing studies often overlook the impact of participating entity behaviors on overall security, lacking a systematic characterization of the complex threat landscape introduced by TEEs. To address this gap, we present a survey of TEE-assisted computation over ciphertext from this behavioral perspective, providing an in-depth analysis of the limitations of current trust models. To comprehensively characterize the complex threats introduced by TEEs, we propose a security framework driven by these entity behaviors. By defining the capabilities and goals of each entity, this framework systematizes the threat models of TEE-assisted ciphertext computation systems into three core trust assumptions: the honest, the semi-honest, and the malicious assumption. Based on this framework, we systematically classify TEE-assisted ciphertext computation protocols across typical scenarios. We evaluate their design features and security under different trust assumptions, and briefly discuss potential open challenges in this domain.