Intel TDX

Intel TDX encrypts the entire virtual machine memory using a hardware-managed encryption key that is inaccessible to the hypervisor, host OS, and other VMs. Unlike process-based enclaves, TDX protects a complete, unmodified guest OS and its workloads. The CPU enforces cryptographic integrity on memory pages, preventing replay, relocation, and tampering attacks. This creates a Trust Domain—a hardware-isolated execution environment where even a compromised hypervisor cannot read or alter VM state.

TDX dramatically shrinks the Trusted Computing Base (TCB) by removing the hypervisor from the security boundary. In traditional virtualization, the VMM has unrestricted access to VM memory. With TDX, the CPU itself enforces isolation, meaning the only trusted components are the Intel TDX Module (a small, formally verified firmware layer) and the CPU package. This eliminates entire classes of attacks originating from hypervisor vulnerabilities, misconfigurations, or malicious insiders with cloud administrator privileges.

Before a workload is deployed or secrets are released, TDX provides hardware-rooted attestation. The CPU generates a cryptographically signed TD Report containing measurements of the Trust Domain's initial state, including the guest firmware and OS image. A remote party can verify this quote against Intel's provisioning service to confirm:

• The VM is running on genuine Intel hardware with TDX enabled
• The exact software stack loaded matches a known-good configuration
• No tampering has occurred during boot This enables zero-trust deployment where workloads only execute on verified platforms.

TDX introduces Secure EPT (Extended Page Tables) to manage memory virtualization within the Trust Domain. Critically, it also defines a secure mechanism for injecting interrupts and exceptions. When an external interrupt occurs, the CPU transitions through the TDX module, which scrubs register state to prevent information leakage before delivering the interrupt to the guest. This prevents the hypervisor from mounting side-channel attacks by manipulating interrupt timing or injecting malicious exception vectors to probe Trust Domain state.

While Trust Domain memory is private by default, VMs need to communicate with the outside world for I/O. TDX provides explicit shared memory regions that the guest OS designates as accessible to the hypervisor. The guest maintains full control over which pages are shared, and the CPU enforces that only designated pages lose their confidentiality protections. This allows standard virtio drivers for network and storage to function with minimal modification, while the guest's sensitive data structures remain encrypted and integrity-protected.

TDX supports live migration of Confidential VMs between physical hosts without exposing memory contents. The migration process uses a Migration TD—a special-purpose Trust Domain that securely transfers encrypted memory pages and VM state. The source and destination platforms perform mutual attestation, and the migration agent negotiates a transport encryption key. This ensures that even during migration, the hypervisor and network intermediaries never access plaintext VM data, enabling cloud operators to perform maintenance without violating confidentiality.

The cryptographic process of verifying the identity and integrity of a Trusted Execution Environment before trusting it with sensitive data. Attestation produces a signed report containing enclave measurements that a remote party can validate against known-good values. Intel TDX uses a hardware-rooted attestation flow through the Intel SGX quoting infrastructure.

• Verifies hardware, firmware, and software integrity
• Produces cryptographically signed evidence
• Prerequisite for releasing secrets to a TEE

AMD's Secure Encrypted Virtualization with Secure Nested Paging adds memory integrity protection to encrypted VMs. It prevents hypervisor-based attacks like data replay, memory remapping, and page table manipulation. SEV-SNP is the primary competitor to Intel TDX, offering similar confidential VM capabilities on AMD EPYC processors.

• Memory encryption with integrity protection
• Prevents malicious hypervisor attacks
• Comparable to Intel TDX on AMD platforms

A virtual machine instance backed by hardware-based memory encryption, ensuring data remains encrypted while in use. The hypervisor cannot access VM memory, protecting workloads from cloud provider insiders and compromised infrastructure. Intel TDX enables CVMs by encrypting the full VM state with a hardware-generated key inaccessible to the VMM.

• Full VM memory encryption at runtime
• Isolated from cloud provider hypervisor
• No application modification required

The set of all hardware, firmware, and software components critical to a system's security. A smaller TCB reduces the attack surface and simplifies formal verification. Intel TDX dramatically shrinks the TCB for virtualized workloads by removing the hypervisor from the trust boundary, leaving only the CPU package and TDX module.

• Minimizes components that must be trusted
• Smaller TCB = fewer potential vulnerabilities
• TDX excludes the VMM from the TCB

A software development kit providing APIs and tools for building AI applications that run within a TEE. It ensures model weights and inference data remain encrypted during computation. When combined with Intel TDX, the SDK enables confidential inference services where proprietary models process sensitive queries without exposing either to the infrastructure operator.

• APIs for enclave-aware AI workloads
• Protects model IP and user data simultaneously
• Enables confidential model serving pipelines