Hi William,
Since Mbed TLS is a cross-platform library, we don't deal directly with TrustZone-M.
However, if I have understood correctly, I think your usecase is solved by the Trusted Firmware M (TF-M) project[1], which is an implementation of secure firmware that provides cryptography services via non-secure-callable APIs.
TF-M uses Mbed TLS internally and implements the PSA Certified Cryptography API[2]. The Crypto Service Integration Guide[3] in the documentation should be a good starting point for what you are trying to do.
I hope that helps,
David Horstmann Mbed TLS developer
[1] https://www.trustedfirmware.org/projects/tf-m [2] https://www.psacertified.org/getting-certified/crypto-api-compliance/ [3] https://trustedfirmware-m.readthedocs.io/en/latest/integration_guide/service... [https://www.trustedfirmware.org/images/social-media-image.png]https://www.trustedfirmware.org/projects/tf-m TrustedFirmware-M (TF-M)https://www.trustedfirmware.org/projects/tf-m TrustedFirmware-M (TF-M) implements the Secure Processing Environment (SPE) for Armv8-M, Armv8.1-M architectures or dual-core platforms. www.trustedfirmware.org
________________________________ From: Lee, William via mbed-tls mbed-tls@lists.trustedfirmware.org Sent: 24 September 2024 15:08 To: mbed-tls@lists.trustedfirmware.org mbed-tls@lists.trustedfirmware.org Subject: [mbed-tls] Looking for suggestions about make Mbed TLS APIs non-secure callable APIs on armv8m
Hi Mbed TLS,
I am looking for some suggestions about make some (or all) Mbed TLS APIs non-secure callable APIs on armv8m.
The background is that I am going to have a secure firmware that provides encryption services by building part (or whole) of Mbed TLS into that firmware and make those original mbedtls_x APIs non-secure callable, so the existing non-secure firmware could link those non-secure callable APIs and use them.
Some of my thoughts: (1) The easiest way to do it I can think of is just add the attribute "cmse_nonsecure_call" to those APIs' declaration (or use a macro to wrap the attribute for conditional build to not impact others don't want it), but I do not think this modification could be accepted by upstream 🙂. (2) So my another thought is duplicate all header files and put them under another folder, assuming it is my-include folder, then I can do whatever I want to my-include folder, but there is also a problem I can think of: a merge/compare burden between include and my-include folder after I have updated Mbed TLS.
I really appreciate other suggestions!
Thanks, William