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VAES

Architecture referenceFeex

VAES provides vector-encoded AES round operations, allowing independent AES blocks to be processed in wider registers where the supported form permits. It is separately identified from legacy AES-NI.

What you need to know

VAES provides vector-encoded AES round operations, allowing independent AES blocks to be processed in wider registers where the supported form permits. It is separately identified from legacy AES-NI.

How it works

Wider VAES operations apply AES rounds independently to 128-bit blocks within a vector. They do not change the AES block size or combine those blocks into a new cipher. VEX and EVEX forms have their own feature and state requirements, and the surrounding mode determines whether independent blocks are available to process together.

Where it is useful

Counter-based modes can provide multiple independent blocks to a vectorized implementation. A serial dependency in a mode or a very small message can limit that opportunity. Authentication, key expansion and memory handling remain separate parts of the implementation.

How to check support and enablement

CPUID.07H.00H:ECX bit 9 enumerates VAES. Also follow the SDM's prerequisites for the selected VEX or EVEX form, including the relevant AES/vector capability and OS-enabled state. Dispatch by the exact instruction form, not the generic feature name alone.

Use a maintained cryptographic implementation that handles feature selection, failure conditions and the complete algorithm. Hardware acceleration supplies primitives; key management, authentication, nonce rules and protocol choices remain software responsibilities.

What the feature does not establish

VAES does not mean AES has a larger block size, a stronger key or automatic acceleration for every encrypted application. It does not establish VPCLMULQDQ or every AVX-512 subset, and it does not supply nonce management or protocol authentication.

Compatibility and performance in practice

A feature field is not a product certification or evidence that a particular application is secure. Performance depends on message sizes, mode, batching and the rest of the protocol. Check the actual provider and keep its security updates current.

A practical verification checklist

  1. Record the exact processor or platform model and the application, OS and runtime versions involved. Preserve the wording of the actual error or requirement.
  2. Check the manufacturer reference for that exact model, then inspect the effective capability and enabled state in the environment where the program runs.
  3. Compare every requirement of the selected binary or backend. A similarly named feature, alias or broad technology label is not enough.
  4. Confirm the application selected the intended implementation. Use its documented diagnostics and a supported fallback when requirements are not met.
  5. Make one supported change at a time and repeat the same workload. Keep the original configuration and recovery path available.

If the feature is listed but software cannot use it

Start with the exact failing component. A hardware database describes recorded capability; the operating system or hypervisor can expose a different effective environment. An illegal-instruction error also needs investigation of the actual faulting instruction and binary build, because corruption or an unrelated unsupported instruction can produce a similar symptom.

Install the application, driver or runtime version supported for the exact platform, and use the vendor's documented baseline or fallback build if needed. A software update cannot create an instruction that the processor lacks. Firmware and security-policy changes should follow the system manufacturer's procedure and a recovery plan rather than a generic optimization recipe.

Sources and scope of this explanation

Intel 64 and IA-32 Architectures Software Developer's Manual · Linux kernel: using XSTATE features in user space

These references establish architectural behavior and software requirements. They do not independently verify every feature value on a linked hardware model page. For model support, use that page's manufacturer evidence and check the effective system configuration. This article does not supply a benchmark, certification or independent review date.

Sources and verification

Editorial ownership: Feex. No independent review date is recorded. How we research.

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