tree e159edf29a7b578d5ccd138238955e770a6e3fe7
parent 05916637e44597537e58601dc63da69489b00950
author Manish V Badarkhe <Manish.Badarkhe@arm.com> 1697634705 +0100
committer Manish V Badarkhe <Manish.Badarkhe@arm.com> 1701710204 +0000

feat(tc): provide a mock mbedtls-random generation function

Simulated the utilization of an external RNG through the
MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG configuration option in mbedTLS.
Consequently, an implementation of mbedtls_psa_external_get_random()
is provided. Given the absence of actual external RNG support,
we provide a mock implementation by utilizing the system counter to
fill the the buffer to provide a random number, specifically tailored
for the use exclusively within the TF-M testsuite.
While this method is not ideal for generating random numbers,
alternatives like the 'rand' library function are not feasible due to
lack of support in TF-A. Additionally, the architectural 'rand'
instruction is not viable, as it is only supported for platforms with
Armv8.5-a+ architecture as an optional feature.
mbedtls_psa_external_get_random() function comes into play during the
exportation of the public portion of the delegated attestation key.

This helps in using mbedTLS-3.4.1 for running the delegated attestation
tests on TC platform.

Change-Id: Ifcf4e3231aad93595e00c353a4b0c606c0ef9fc2
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>