Example for wolfCrypt PUF on STM32H5

[dgarske]

No description provided.

[danielinux]

Check availability of PUF_TEST=0 option

[Copilot]

Pull request overview

Note

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Adds a new bare‑metal SRAM PUF example demonstrating wolfCrypt’s PUF enrollment/reconstruction and key derivation on STM32H5 (NUCLEO‑H563ZI).

Changes:

• Adds a self-contained PUF example app (startup, linker script, STM32 UART/TRNG HAL, wolfCrypt settings).
• Adds build system + documentation for test mode vs real SRAM mode.
• Updates top-level docs and ignores the example’s build output directory.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
puf/user_settings.h	Minimal wolfCrypt configuration enabling SRAM PUF + dependencies for bare-metal use
puf/stm32.c	STM32H5 bare-metal UART printf retarget + TRNG-based custom RAND block generator + HAL init
puf/startup.c	Minimal Cortex‑M startup: vector table, Reset_Handler, SystemInit
puf/main.c	PUF demo flow (test mode synthetic SRAM; hardware path reads NOLOAD SRAM section)
puf/linker.ld	Linker script reserving a NOLOAD SRAM region for PUF raw bytes
puf/README.md	Build/flash/run docs for the example + API usage notes
puf/Makefile	Standalone build for the example (PUF_TEST switch, pulls required wolfCrypt sources)
README.md	Adds a pointer to the new puf/ example
.gitignore	Ignores puf/Build artifacts

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[danielinux]

Tested with emulator:

• make -C puf PUF_TEST=0
  The build switch is now wired correctly in puf/Makefile:29 and documented in puf/README.md:39. The hardware path now includes an explicit reconstruction/self-check flow in puf/main.c:277.

  I reran it under m33mu:

  - --puf-seed 0x1
      - enrollment identity: 0953b0685892eff9259d7f21642795bdacb2d86dd50b31229e25937a9bf1f5b7
      - reconstructed identity matched
      - enrollment key: 370a69677beeb5af426bb65a7579b80ca88329708b598de8087faffa82062c7f
      - reconstructed key matched
  - --puf-seed 0x1 --puf-noise 2
      - enrollment identity: 49760781a942fb63e5a96e7c8d46dde422978ca79c353290f8019b0d01519098
      - reconstructed identity matched
      - enrollment key: f295936a25161baf212147a8a0c0d89577f7f9932b378e6714742285e22ae23b
      - reconstructed key matched
  - --puf-seed 0x1 --puf-cold-boot 1 --puf-noise 2
      - enrollment identity: 56feda60f16fa40ab1e4a6e8d2490d0c239ecae540dc7a630ede49b39d80557a
      - reconstructed identity matched
      - enrollment key: 691bdf4454563ab133536267327cb614ae5b455204f6d2e447aa057185f284a2
      - reconstructed key matched

So the reconstruction comments were addressed in the code, and the updated example passes under m33mu with deterministic SRAM and with seeded noise.