Confidential Computing

The foundational component of confidential computing. A Trusted Execution Environment (TEE) is a secure, isolated area within a main processor, created using hardware extensions like Intel SGX, AMD SEV, or Arm CCA. It ensures that code and data loaded inside are protected with confidentiality, integrity, and attestation, even from the host operating system, hypervisor, or cloud provider.

A cryptographic protocol that allows a client to verify the integrity and authenticity of the software running inside a remote TEE. It proves that:

• The correct application is running.
• It is executing within a genuine, secure hardware enclave.
• The initial state (code and data) has not been tampered with. This enables trusted deployment of sensitive workloads in untrusted environments like public clouds.

Data is encrypted while in memory and is only decrypted inside the secure CPU boundary of the TEE. This provides:

• Confidentiality: Prevents unauthorized read access, including from privileged system software and physical attacks like cold-boot attacks.
• Integrity: Ensures data cannot be altered outside the TEE without detection. Any unauthorized modification triggers an integrity failure, halting execution.

A critical memory management feature in TEEs like Intel SGX. The Enclave Page Cache (EPC) is a reserved, encrypted region of physical memory that stores pages belonging to an enclave. The Memory Encryption Engine (MEE) transparently encrypts/decrypts data moving between the CPU and EPC, ensuring data is only in plaintext within the CPU itself.

Key management operations specific to TEEs:

• Sealing: The process of encrypting data by the enclave, using a key derived from the enclave's identity and the platform hardware, for persistent storage. Only the same enclave (or a designated successor) on the same platform can unseal it.
• Provisioning: The secure process of delivering secrets (e.g., keys, credentials) into an attested enclave, often via a trusted service.

Confidential computing enables new trust models for multi-party collaboration:

• Privacy-Preserving Analytics: Joint analysis of sensitive datasets (e.g., healthcare, finance) without exposing raw data.
• Secure AI/ML: Training models on encrypted data or protecting proprietary model IP during inference.
• Blockchain & DeFi: Enabling private smart contracts and confidential transactions (e.g., Oasis Network, Secret Network).
• Digital Rights Management (DRM): Protecting high-value media content during playback.

Remote Attestation is a cryptographic protocol that allows a remote verifier to confirm the identity and integrity of a TEE and the application running inside it. It proves that:

• The code is running on genuine hardware.
• The software stack is in a known, unaltered state.
• The enclave's measurements match a trusted source. This enables secure provisioning of keys and sensitive data from external services.

Intel Software Guard Extensions (SGX) is a set of CPU instructions that create hardware-isolated enclaves within an application's address space. Key features include:

• Memory Encryption: Enclave data in RAM is encrypted.
• Access Control: The CPU enforces access, preventing even privileged OS or hypervisor code from reading enclave memory.
• Sealing: Data can be encrypted for persistent storage, bound to the specific enclave and platform. It's a foundational TEE technology for cloud and blockchain applications.

AMD Secure Encrypted Virtualization (SEV) is a hardware feature that encrypts the memory of individual virtual machines (VMs) with a unique key. Unlike per-application enclaves (SGX), SEV protects entire VMs, making it suitable for confidential VMs in cloud environments. The hypervisor manages the VMs but cannot access their encrypted memory contents, providing isolation from the cloud provider.

A core principle of Confidential Computing is partitioning an application into a trusted and an untrusted component.

• Trusted Component: Runs inside the secure TEE, handling sensitive logic (e.g., private key operations, model inference).
• Untrusted Component: Manages non-sensitive tasks, networking, and UI outside the enclave. This minimizes the trusted computing base (TCB), reducing the attack surface. Communication between parts occurs via a controlled interface.

A Trusted Execution Environment (TEE) is a secure, isolated area within a main processor. It ensures the confidentiality and integrity of code and data loaded inside it, even from the host operating system. This hardware-enforced isolation is the foundational technology for confidential computing.

• Examples: Intel SGX, AMD SEV, ARM TrustZone.
• Key Property: Provides attestation, allowing remote parties to cryptographically verify the integrity of the TEE's software state.

A Secure Enclave is a specific implementation of a TEE, often referring to Apple's proprietary hardware-based security technology. It provides a coprocessor with encrypted memory and a secure boot process, separate from the main processor. While often associated with mobile devices for biometric data, the architectural principle is core to confidential computing.

• Function: Stores cryptographic keys and performs sensitive operations like biometric matching.
• Isolation: Uses a dedicated secure kernel and memory.

A Zero-Knowledge Proof is a cryptographic method where one party (the prover) can prove to another (the verifier) that a statement is true without revealing any information beyond the validity of the statement itself. While TEEs protect data during computation, ZKPs protect data by verifying results without exposing inputs.

• Use Case: Enables privacy in blockchain transactions (e.g., zkRollups) and identity verification.
• Contrast with TEEs: ZKPs are cryptographic, not hardware-based; they prove correctness without needing to trust hardware.

Fully Homomorphic Encryption (FHE) is a form of encryption that allows computations to be performed directly on encrypted data without needing to decrypt it first. The result of the computation remains encrypted and, when decrypted, matches the result of operations performed on the plaintext.

• Key Benefit: Provides the strongest theoretical privacy guarantee, as data is never decrypted on the server.
• Practical Challenge: Historically computationally intensive, though performance is improving with new schemes and hardware acceleration.

Remote Attestation is a cryptographic protocol that allows a remote party (a verifier) to gain confidence that a software application is running securely within a genuine TEE. It produces a signed report containing the TEE's measurements (like a hash of the initial code and data).

• Core Mechanism: Uses a hardware-rooted trust anchor (e.g., an EPID key for Intel SGX) to sign the attestation report.
• Purpose: Enables trust in cloud-based confidential computing by verifying the integrity and identity of the secure environment before sending sensitive data.

Confidential VMs and Confidential Containers are cloud service offerings that leverage TEEs or memory encryption to protect entire virtual machines or containerized workloads from the cloud provider's infrastructure. They encrypt the VM's memory and vCPU state.

• Provider Examples: Azure Confidential Compute, Google Confidential VMs, AWS Nitro Enclaves.
• Scope: Protects the entire workload runtime (OS, app, data) rather than a single application process, simplifying adoption for legacy applications.