SGX

Intel Software Guard Extensions (SGX) is a set of processor features that enable the creation of enclaves—protected regions of execution in memory. Enclaves are designed to protect code and data from a potentially compromised system, including the operating system and hypervisor. SGX provides confidentiality and integrity for the contents of an enclave, even when the surrounding software stack is untrusted.

Enclave memory is managed under a protected area called the enclave page cache (EPC). Data and instructions inside an enclave are visible only to the code running within that enclave. Access to enclaves occurs through specific instructions, such as ECALL and EENTER to enter an enclave and EEXIT to leave it, with the processor enforcing strict isolation to prevent leakage or tampering by non-enclave code.

SGX includes mechanisms for attestation and sealing. Attestation allows an enclave to prove to a remote party that it is genuine and running on a particular platform, using local or remote attestation, historically supported by mechanisms such as EPID or DCAP. Sealing provides a means to persistently store secrets by deriving cryptographic keys from the enclave identity and the platform state, enabling encrypted data to be recovered only by authorized enclaves on trusted platforms.

Development and deployment of SGX-enabled applications are supported by dedicated SDKs and toolchains, with adoption in various cloud and on-premises environments. While SGX can protect sensitive computations, it has limitations, including finite enclave memory resources, potential performance overheads, and exposure to certain side-channel attacks. Designing secure SGX applications requires careful handling of code, data, and interaction with untrusted software.