Remote Attestation

Binds a unique, asymmetric key pair to the Trusted Execution Environment (TEE) and the specific hardware platform. The private key is generated and sealed within the hardware root of trust and never leaves the secure perimeter. The relying party uses the corresponding public key to verify that the attestation report originated from a genuine, non-emulated processor.

• Prevents replay attacks from cloned or simulated enclaves
• Rooted in fuse-derived keys burned into the silicon during manufacturing
• Enables sealing policies that bind data to a specific platform instance

Generates a cryptographically secure hash of the entire Trusted Computing Base (TCB) loaded into the enclave, including the initial code, static data, and launch configuration. This measurement is included in the signed attestation report. Any modification to a single bit of the software stack—whether a malicious injection or a benign update—produces a completely different hash, immediately signaling a compromise.

• Uses a cumulative hash extending Platform Configuration Registers (PCRs)
• Enables code transparency by comparing the measurement against a public, auditable manifest
• Detects supply chain attacks that swap container images or libraries

Ensures the attestation report is generated in real-time and not a recording of a previous, legitimate session. The verifier sends a cryptographic nonce (a random number used once) to the attester, which must be included in the signed report. This proves the enclave is alive and responsive at the moment of verification, defeating adversaries who have captured valid historical attestation data.

• Nonce is generated by the relying party immediately before the challenge
• Binds the attestation to a specific TLS session or API request
• Prevents cut-and-paste attacks where a compromised host replays an old, valid report

Establishes a transitive trust path from the hardware root to the application enclave through a sequence of signed measurements. The platform's Authenticated Code Module (ACM) verifies the firmware, which verifies the bootloader, which verifies the OS or hypervisor, which finally launches and measures the application enclave. Each link in this chain signs the hash of the next stage.

• Validates the entire boot integrity chain before application attestation
• Prevents BIOS/UEFI rootkits from subverting the TEE
• The final attestation report includes the full lineage of measurements

Extends attestation into a persistent storage primitive. Data is encrypted by the TEE and bound to the specific enclave identity and software measurement. The decryption key is only released by the hardware if the requesting enclave presents the exact same identity and measurement hash. This ensures that a compromised or updated version of the code cannot access the secrets of its predecessor.

• Binds data to MRENCLAVE (enclave code identity) or MRSIGNER (author identity)
• Protects model weights and user data at rest outside the TEE boundary
• Enables secure state recovery across power cycles without exposing secrets to the OS

Decouples the verification logic from the relying party by using a trusted, centralized service that validates attestation reports against a database of known-good measurements and revoked platform keys. This service acts as a policy decision point, translating raw cryptographic evidence into a simple yes/no trust decision for the application.

• Examples include Intel Trust Authority, Azure Attestation, and Google Cloud External Key Manager
• Manages the complexity of parsing vendor-specific quote formats
• Provides a centralized point for auditing and logging all trust decisions

A structured challenge-response handshake that proves an enclave's genuineness. The process follows a strict sequence:

• Challenge Generation: The relying party (client) generates a cryptographic nonce and sends it to the TEE-hosted service.
• Evidence Collection: The TEE's hardware gathers claims about the enclave's identity (MRENCLAVE/MRSIGNER), platform firmware, and security version numbers.
• Quote Generation: The CPU signs this collection of claims, including the client's nonce, with a Report Key derived from a fused, device-unique root key.
• Verification: The client validates the signature against the manufacturer's certificate chain (e.g., Intel PCS, AMD KDS) and compares the enclave measurements against a trusted Code Transparency log.

The core of attestation is the cryptographic measurement of the enclave's initial state. During build time, a hash is computed over the code, stack, and heap pages loaded into the secure memory region.

• MRENCLAVE (Intel SGX): A 256-bit SHA-2 hash representing the exact identity of the enclave code and its initial configuration. Any code change produces a distinct MRENCLAVE.
• MRSIGNER (Intel SGX): The hash of the public key of the authority that signed the enclave, enabling versioning and author verification without changing the signer identity.
• AMD SEV-SNP Measurement: A hash of the initial VM memory and CPU register state, cryptographically bound to the guest policy.

A critical infrastructure component that offloads the complex cryptographic validation from individual clients. An AVS acts as a trusted intermediary that:

• Parses TEE Quotes: Decodes the binary attestation evidence from various hardware formats (SGX, SEV-SNP, TDX).
• Validates Certificate Chains: Verifies the quote's signature against the chip manufacturer's root Certificate Authority and checks for platform revocation lists (CRLs).
• Appraises Policies: Compares the measured enclave identity against a user-defined policy (e.g., 'only allow MRENCLAVE X with Security Version >= 5').
• Issues Attestation Tokens: Returns a simplified, signed JSON Web Token (JWT) to the client, confirming the appraisal result.

Attestation enables secure provisioning, where secrets are released only to a verified TEE. This prevents a malicious host OS or a spoofed enclave from extracting keys.

• Sealing: The TEE encrypts data locally to its own identity, ensuring only the same enclave on the same CPU can unseal it after a reboot.
• Secure Key Release: A remote Key Management Service (KMS) validates the attestation quote before releasing a decryption key over an Enclave TLS channel.
• Discard Resistance: The protocol ensures that if attestation fails, the secret is never transmitted, preventing replay attacks against a compromised host.

In Confidential AI, remote attestation proves that a model is running in a genuine TEE, protecting both the proprietary weights and the user's prompt.

• Model Provider Assurance: The provider verifies the enclave measurement before releasing the encrypted model weights, preventing theft by a cloud administrator.
• User Data Privacy: The end-user attests the enclave before sending a sensitive prompt, ensuring the host OS cannot log the plaintext query.
• End-to-End Verifiability: The attestation report includes the hash of the inference code, proving that the exact, unmodified model is executing without backdoors.

Remote attestation secures Federated Learning rounds by validating the integrity of client nodes before accepting their model updates.

• Node Validation: The aggregation server attests each participating device to ensure it runs the genuine FL client software, blocking malicious nodes from submitting poisoned gradients.
• Hardware-Graded Trust: Attestation provides a hardware-backed trust score, allowing the server to weight updates from TEE-protected nodes more heavily.
• Audit Trail: The signed attestation quotes serve as a non-repudiable log, proving that a specific device on a specific platform contributed a specific update.

A physically immutable, inherently trusted source within a computing platform that serves as the foundation for all subsequent security operations. This is typically a set of fused cryptographic keys burned into the silicon during manufacturing that cannot be altered or extracted.

• Provides the anchor for secure boot and measured boot
• Generates the Endorsement Key used in attestation signing
• Ensures the chain of trust begins in hardware, not software

A cryptographically signed data structure generated by a TEE that proves its identity, integrity, and the exact software stack it is running. The report is signed by a key derived from the hardware root of trust and includes:

• Enclave Identity: A hash of the enclave's initial code and data
• Platform TCB Info: Versions of firmware, microcode, and hardware
• User Data: Optional nonce or public key from the challenger to prevent replay attacks

The set of all hardware, firmware, and software components that are critical to a system's security. A single vulnerability in any TCB component can compromise the entire system's security guarantees. Remote attestation allows a relying party to verify the TCB version before trusting the environment.

• Smaller TCB = smaller attack surface
• Includes CPU microcode, TEE firmware, and the attested application
• Excludes the host OS, hypervisor, and other VMs in confidential computing

A TEE-specific operation that encrypts data and binds it to the exact enclave identity and platform that generated it. Sealed data can only be decrypted by the same enclave on the same hardware, ensuring that sensitive material like model weights or encryption keys cannot be accessed outside the attested environment.

• Seal to Enclave Identity: Data bound to a specific code version
• Seal to Signing Identity: Data bound to the enclave author's key
• Enables secure local persistence without trusting the host OS

The process of securely injecting secrets, configuration data, and cryptographic keys into a TEE only after its identity and integrity have been verified through remote attestation. This ensures that sensitive material is never exposed to an untrusted host.

• Attestation report is validated by a Key Management Service (KMS)
• Secrets are released only if the TCB version is within an acceptable policy
• Forms the foundation for Confidential AI model deployment