pk: add alternate function for keypair generation using PSA

Instead of using the legacy mbedtls_ecp_gen_keypair() which makes
use of ECP's math, when USE_PSA_CRYPTO is enabled then the new
function pk_genkey_ec() is used in test_suite_pk.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>

tests/suites/test_suite_ecp.function

@@ -987,7 +987,7 @@ exit:
 }
 /* END_CASE */
 
-/* BEGIN_CASE */
+/* BEGIN_CASE depends_on:!MBEDTLS_USE_PSA_CRYPTO */
 void mbedtls_ecp_gen_keypair(int id)
 {
     mbedtls_ecp_group grp;
@@ -1016,7 +1016,7 @@ exit:
 }
 /* END_CASE */
 
-/* BEGIN_CASE */
+/* BEGIN_CASE depends_on:!MBEDTLS_USE_PSA_CRYPTO */
 void mbedtls_ecp_gen_key(int id)
 {
     mbedtls_ecp_keypair key;

tests/suites/test_suite_pk.function

@@ -17,9 +17,63 @@
  * unconditionally (https://github.com/Mbed-TLS/mbedtls/issues/2023). */
 #include "psa/crypto.h"
 
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#include "mbedtls/psa_util.h"
+#endif
+
 #define RSA_KEY_SIZE 512
 #define RSA_KEY_LEN   64
 
+static int pk_genkey_ec(mbedtls_ecp_group *grp,
+                        mbedtls_mpi *d, mbedtls_ecp_point *Q)
+{
+    psa_status_t status;
+    psa_key_attributes_t key_attr = PSA_KEY_ATTRIBUTES_INIT;
+    mbedtls_svc_key_id_t key_id = MBEDTLS_SVC_KEY_ID_INIT;
+    size_t curve_bits;
+    psa_ecc_family_t curve = mbedtls_ecc_group_to_psa(grp->id,
+                                                      &curve_bits);
+    unsigned char key_buf[MBEDTLS_PSA_MAX_EC_PUBKEY_LENGTH];
+    size_t key_len;
+    int ret;
+
+    psa_set_key_type(&key_attr, PSA_KEY_TYPE_ECC_KEY_PAIR(curve));
+    psa_set_key_bits(&key_attr, curve_bits);
+    psa_set_key_usage_flags(&key_attr, PSA_KEY_USAGE_EXPORT);
+
+    status = psa_generate_key(&key_attr, &key_id);
+    if (status != PSA_SUCCESS) {
+        return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
+    }
+
+    status = psa_export_key(key_id, key_buf, sizeof(key_buf), &key_len);
+    if (status != PSA_SUCCESS) {
+        psa_destroy_key(key_id);
+        return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
+    }
+
+    ret = mbedtls_mpi_read_binary(d, key_buf, key_len);
+    if (ret != 0) {
+        return ret;
+    }
+
+    status = psa_export_public_key(key_id, key_buf, sizeof(key_buf),
+                                   &key_len);
+    if (status != PSA_SUCCESS) {
+        psa_destroy_key(key_id);
+        return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
+    }
+
+    ret = mbedtls_ecp_point_read_binary(grp, Q, key_buf, key_len);
+    if (ret != 0) {
+        return ret;
+    }
+
+    psa_destroy_key(key_id);
+
+    return 0;
+}
+
 /** Generate a key of the desired type.
  *
  * \param pk        The PK object to fill. It must have been initialized
@@ -53,12 +107,18 @@ static int pk_genkey(mbedtls_pk_context *pk, int parameter)
             return ret;
         }
 
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+        return pk_genkey_ec(&mbedtls_pk_ec(*pk)->grp,
+                            &mbedtls_pk_ec(*pk)->d,
+                            &mbedtls_pk_ec(*pk)->Q);
+#else /* MBEDTLS_USE_PSA_CRYPTO */
         return mbedtls_ecp_gen_keypair(&mbedtls_pk_ec(*pk)->grp,
                                        &mbedtls_pk_ec(*pk)->d,
                                        &mbedtls_pk_ec(*pk)->Q,
                                        mbedtls_test_rnd_std_rand, NULL);
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
     }
-#endif
+#endif /* MBEDTLS_ECP_C */
     return -1;
 }
 
@@ -462,6 +522,10 @@ void pk_utils(int type, int parameter, int bitlen, int len, char *name)
 {
     mbedtls_pk_context pk;
 
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    PSA_INIT();
+#endif
+
     mbedtls_pk_init(&pk);
 
     TEST_ASSERT(mbedtls_pk_setup(&pk, mbedtls_pk_info_from_type(type)) == 0);
@@ -475,6 +539,9 @@ void pk_utils(int type, int parameter, int bitlen, int len, char *name)
 
 exit:
     mbedtls_pk_free(&pk);
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    PSA_DONE();
+#endif
 }
 /* END_CASE */
 
@@ -1234,9 +1301,8 @@ void pk_psa_sign(int parameter_arg,
         mbedtls_pk_init(&pk);
         TEST_ASSERT(mbedtls_pk_setup(&pk,
                                      mbedtls_pk_info_from_type(MBEDTLS_PK_ECKEY)) == 0);
-        TEST_ASSERT(mbedtls_ecp_gen_key(grpid,
-                                        (mbedtls_ecp_keypair *) pk.pk_ctx,
-                                        mbedtls_test_rnd_std_rand, NULL) == 0);
+        TEST_ASSERT(pk_genkey(&pk, grpid) == 0);
+
         alg_psa = PSA_ALG_ECDSA(PSA_ALG_SHA_256);
     } else
 #endif /* MBEDTLS_PK_CAN_ECDSA_SIGN */