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These do not link directly against Mbed TLS so need their own propagation of the custom config values through CMake. Signed-off-by: David Horstmann <david.horstmann@arm.com>
The files within the p256-m/ subdirectory originate from the p256-m GitHub repository, which is distributed under the Apache 2.0 license. They are authored by Manuel Pégourié-Gonnard. p256-m is a minimalistic implementation of ECDH and ECDSA on NIST P-256, especially suited to constrained 32-bit environments. Mbed TLS documentation for integrating drivers uses p256-m as an example of a software accelerator, and describes how it can be integrated alongside Mbed TLS. It should be noted that p256-m files in the Mbed TLS repo will not be updated regularly, so they may not have fixes and improvements present in the upstream project.
The files p256-m.c and .h, along with the license, have been taken from the p256-m repository.
It should be noted that p256-m deliberately does not supply its own cryptographically secure RNG function. As a result, the PSA RNG is used, with p256_generate_random() wrapping psa_generate_random().