Hi experts,

I wanted to forward some crypto operations to an external driver that provides psa_call APIs. The mbedtls version I am using 3.4.0.

 Take  psa_asymmetric_encrypt as an example, The mbedtls api is

psa_status_t psa_asymmetric_encrypt(mbedtls_svc_key_id_t key,

                                    psa_algorithm_t alg,

                                    const uint8_t *input,

                                    size_t input_length,

                                    const uint8_t *salt,

                                    size_t salt_length,

                                    uint8_t *output,

                                    size_t output_size,

                                    size_t *output_length)

It gets attribute, key.data and key.byte from key_id. Then call function psa_driver_wrapper_asymmetric_encrypt without key_id as its argument:

    status = psa_driver_wrapper_asymmetric_encrypt(

        &attributes, slot->key.data, slot->key.bytes,

        alg, input, input_length, salt, salt_length,

        output, output_size, output_length);

In psa_driver_wrapper_asymmetric_encrypt, it will use different implementations according to the location value in https://github.com/Mbed-TLS/mbedtls/blob/d69d3cda34c400a55220352518e37d3d2ccea5d2/scripts/data_files/driver_templates/psa_crypto_driver_wrappers.h.jinja#L2503C13-L2503C21.

I define a new location definition(RSS_PSA_LOCATION. When the location is RSS_PSA_LOCATION,  making it call

psa_status_t crypto_psa_asymmetric_encrypt(psa_key_id_t key,

                                                     psa_algorithm_t alg,

                                                     const uint8_t *input,

                                                     size_t input_length,

                                                     const uint8_t *salt,

                                                     size_t salt_length,

                                                     uint8_t *output,

                                                     size_t output_size,

                                                     size_t *output_length)

This API require key_id. Is it possible to get key_id from attribute and key_slot?

Regards,

Jiamei Xie