Confidential Computing

The CPU creates a private, encrypted enclave within main memory that is inaccessible to all other software, including the OS kernel and hypervisor.

• Enclave Page Cache (EPC): A dedicated, encrypted memory region reserved exclusively for TEE operations
• Hardware-enforced boundaries: Any attempt by non-enclave code to read enclave memory triggers a processor-level access violation
• Example: Intel SGX allocates up to 512MB of private memory per enclave, while AMD SEV encrypts entire virtual machines with per-VM keys

Unlike traditional encryption that protects data at rest (storage) and in transit (network), Confidential Computing encrypts data in use within the CPU itself.

• Transparent encryption engine: A dedicated on-die memory controller automatically encrypts and decrypts data as it moves between cache and RAM
• Per-enclave encryption keys: Each TEE instance gets unique keys, preventing cross-enclave data leakage
• Example: AMD SEV-ES encrypts all CPU register state when a VM stops, preventing the hypervisor from inspecting guest register values

A cryptographic mechanism that allows a remote party to verify that the correct, untampered code is running inside a genuine TEE before sending secrets.

• Hardware-signed measurement: The CPU generates a cryptographic hash of the enclave's initial code and data, signed by a key fused into the processor at manufacture
• Attestation report: Contains the enclave's identity, code measurement, and TCB version, verifiable against the hardware vendor's public key infrastructure
• Example: Intel's Enhanced Privacy ID (EPID) allows anonymous attestation without revealing the specific processor's identity

Confidential Computing radically reduces the attack surface by excluding the operating system, hypervisor, and cloud provider from the trust boundary.

• TCB components: Only the application code, the TEE firmware, and the processor itself must be trusted
• Excluded from TCB: Host OS, device drivers, orchestration layers, and cloud administrator tools
• Security implication: Even a fully compromised host OS cannot read enclave memory or tamper with computation
• Example: AWS Nitro Enclaves have no persistent storage, no interactive access, and no external networking—only a vsock for secure local communication

Beyond confidentiality, TEEs provide cryptographic integrity guarantees that prevent silent data corruption or tampering during computation.

• Memory integrity tree: A Merkle tree structure verifies that data read from encrypted memory has not been modified, replayed, or reordered by a physical attacker
• Replay protection: Hardware counters prevent an attacker from substituting current data with a previously valid encrypted memory state
• Example: Intel SGX2 and TDX implement integrity protection that detects bus-level snooping and cold-boot attacks on memory contents

TEEs protect not only the data being processed but also the proprietary algorithms and models operating on that data.

• Encrypted code loading: Application binaries are decrypted only inside the enclave, preventing reverse engineering by the host
• IP protection for ML models: Neural network weights and architecture remain opaque to infrastructure operators
• Example: Financial institutions use Confidential Computing to run proprietary trading algorithms on sensitive client data without exposing either the model or the data to the cloud provider

Hardware-enforced encryption of data while it resides in system DRAM, preventing physical attackers from extracting plaintext via cold-boot attacks, bus snooping, or DIMM interposers. Key technologies include:

• AMD SME (Secure Memory Encryption): Encrypts entire system memory with a single key
• Intel TME (Total Memory Encryption): Transparently encrypts all data leaving the processor package
• AMD SEV-ES: Encrypts CPU register state on each VM exit

Memory encryption is the last line of defense against physical hardware attacks, ensuring that even a compromised hypervisor or stolen DIMM yields only ciphertext.

A hardware-isolated region of memory and execution within a TEE that is inaccessible to any process outside it, including privileged system software. Enclaves operate with:

• Encrypted memory pages that are decrypted only inside the CPU package
• Hardware-enforced isolation from the OS, hypervisor, and DMA devices
• Sealed storage for persisting encrypted data to untrusted storage

Enclaves are the execution container for confidential workloads. Code and data are loaded into the enclave, verified via attestation, and then executed in complete isolation from the rest of the system.

A cryptographic scheme that allows computation directly on encrypted data without ever decrypting it. Unlike TEEs, which decrypt data inside a secure hardware boundary, homomorphic encryption keeps data encrypted throughout the entire computation lifecycle.

Key distinctions from confidential computing:

• No hardware trust dependency: Security is purely mathematical
• Extreme computational overhead: Operations are 1,000-1,000,000x slower than plaintext
• Complementary use case: Often combined with TEEs for multi-party scenarios

Fully Homomorphic Encryption (FHE) remains an active research area, with practical deployment limited to narrow, low-latency-tolerant applications.