Add RealTek AmebaPro2 (RTL8735B) HUK crypto-callback port

[dgarske]

Add RealTek AmebaPro2 (RTL8735B) HUK crypto-callback port

Summary

Adds a wolfCrypt port that binds keys to the RealTek RTL8735B (AmebaPro2) silicon Hardware Unique Key (HUK) via the crypto-callback (CryptoCb) framework. A 256-bit "seed" is run through the AmebaPro2 HAL secure HKDF key-ladder against the HUK to derive a per-purpose working key in a secure key-storage slot; the working key never enters software.

It is a pure crypto-callback device -- no new wolfSSL core API, no new struct fields, and no changes to any shared core file (only the new port files plus configure.ac/include.am/zephyr build wiring). AES reads its seed from the standard aes->devKey; ECDSA reads a port-defined wc_AmebaPro2_EccKey (the HUK-wrapped scalar + seed) attached via the standard ecc_key->devCtx.

Features

• AES-GCM (full payload), AES-ECB, AES-CBC, AES-CTR under the HUK-derived slot key. GCM/ECB use the HAL secure-key engine; CBC/CTR chain in software over the single-block ECB secure-key op (the HAL has no CBC/CTR secure-key variant), so the key still never leaves hardware. CBC handles in-place (in == out) and multi-call chaining; CTR maintains the partial-block keystream state across calls.
• HUK-bound ECDSA sign (P-256): the wrapped scalar is unwrapped under the HUK into a short-lived buffer, signed, and scrubbed; the blob is device-bound (only unwraps on the silicon whose HUK produced the slot key).
• Unaligned caller buffers are tolerated (the HAL needs 32-byte-aligned DMA buffers; the port bounces through aligned temporaries). A non-12-byte GCM IV is a hard error (no silent software fallback that would key off the seed).

Build options

• WOLFSSL_REALTEK_HUK + WOLF_CRYPTO_CB enable the device (set in user_settings.h); slot/device IDs are overridable (WC_HUK_DEVID, WC_AMEBAPRO2_*).
• --enable-amebapro2 builds a host compile-test against a HAL shim (no vendor SDK needed) to exercise the crypto-callback dispatch and build wiring.

Testing

• Host: --enable-amebapro2 builds clean; default build unaffected.
• RTL8735B silicon (RealTek FreeRTOS SDK and Zephyr): all of AES-GCM/ECB/CBC/CTR (incl. unaligned buffers, in-place + multi-call CBC, non-12-byte-IV reject) and HUK-bound ECDSA (P-256 signature verifies against the original public key; tampered hash fails) PASS.

Documentation

• wolfcrypt/src/port/realtek/README.md -- hardware blocks used, enabling, API (AES + the devCtx ECDSA usage), config macros, notes/limitations, on-target benchmarks, and optimization notes (sp_cortexm.c, Thumb-2 asm).
• wolfssl/wolfcrypt/port/realtek/amebapro2.h -- public API and the wc_AmebaPro2_EccKey context struct.
• Companion SDK-integration example: wolfssl-examples AmebaPro2/.

[Copilot]

Pull request overview

This PR introduces a new wolfCrypt crypto-callback device port for the RealTek AmebaPro2 (RTL8735B) Hardware Unique Key (HUK), enabling hardware-bound AES operations by deriving per-purpose working keys inside the SoC. It also extends shared DHUK (Device Hardware Unique Key) plumbing and improves STM32 bare-metal integration and robustness in related crypto paths.

Changes:

• Add RealTek AmebaPro2 (RTL8735B) HUK CryptoCb device (AES-GCM/ECB/CBC/CTR) plus host compile-test shim and documentation.
• Extend shared DHUK/CCB plumbing (ECC wrapped-private import API, key struct fields, scrubbing) and tighten STM32 family/build-path configuration.
• Improve STM32 bare-metal support (headers/clock macros) and harden STM32 RNG polling/recovery to avoid infinite loops.

Reviewed changes

Copilot reviewed 17 out of 18 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
zephyr/CMakeLists.txt	Adds the AmebaPro2 port source to Zephyr module build.
wolfssl/wolfcrypt/settings.h	Adds STM32 family/build-path gating and implies WOLFSSL_DHUK for RealTek HUK builds.
wolfssl/wolfcrypt/port/st/stm32.h	Expands STM32 bare-metal support macros, DHUK/CCB gating, and related prototypes.
wolfssl/wolfcrypt/port/realtek/amebapro2.h	Public header for registering/unregistering the AmebaPro2 HUK CryptoCb device and config macros.
wolfssl/wolfcrypt/include.am	Registers the new RealTek port header for distribution.
wolfssl/wolfcrypt/ecc.h	Adds DHUK-related fields to ecc_key and declares wrapped-private import APIs.
wolfssl/wolfcrypt/aes.h	Removes legacy STM32U5 DHUK fields and makes devId/devCtx purely CryptoCb-based.
wolfcrypt/src/random.c	Adds bounded polling + recovery for STM32 RNG and pulls in STM32 bare clock-enable macros.
wolfcrypt/src/port/st/README.md	Updates STM32 port documentation (families, BARE/CubeMX, DHUK, CCB).
wolfcrypt/src/port/realtek/README.md	Documents AmebaPro2 HUK port, build options, API usage, and limitations.
wolfcrypt/src/port/realtek/amebapro2.c	Implements the AmebaPro2 HUK CryptoCb device (AES paths; ECDSA sign stub).
wolfcrypt/src/port/realtek/amebapro2_shim.h	Host compile-test HAL shim for --enable-amebapro2.
wolfcrypt/src/include.am	Wires RealTek port sources/docs into the autotools build and distribution lists.
wolfcrypt/src/ecc.c	Adds DHUK/CCB key import helpers, scrubbing, and STM32 PKA input-validation parity.
wolfcrypt/src/aes.c	Routes STM32 bare AES ops through the bare driver, removes legacy DHUK flow, and stages devKey for CryptoCb.
configure.ac	Adds --enable-amebapro2 host compile-test option and wires it to CryptoCb enablement.
.wolfssl_known_macro_extras	Adds additional known macros for tooling/source checks related to new ports/STM32 work.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.