Add & splice in test driver for ECC keygen

Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
diff --git a/tests/src/drivers/keygen.c b/tests/src/drivers/keygen.c
new file mode 100644
index 0000000..4c830c3
--- /dev/null
+++ b/tests/src/drivers/keygen.c
@@ -0,0 +1,129 @@
+/*
+ * Test driver for signature functions
+ */
+/*  Copyright (C) 2020, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_PSA_CRYPTO_DRIVERS) && defined(MBEDTLS_TEST_HOOKS)
+#include "psa/crypto.h"
+#include "mbedtls/ecp.h"
+#include "mbedtls/error.h"
+
+#include "drivers/keygen.h"
+
+#include "test/random.h"
+
+#include <string.h>
+
+/* If non-null, on success, copy this to the output. */
+void *test_driver_keygen_forced_output = NULL;
+size_t test_driver_keygen_forced_output_length = 0;
+
+psa_status_t test_transparent_keygen_status = PSA_ERROR_NOT_SUPPORTED;
+unsigned long test_transparent_keygen_hit = 0;
+
+psa_status_t test_transparent_generate_key(
+    const psa_key_attributes_t *attributes,
+    uint8_t *key, size_t key_size, size_t *key_length )
+{
+    ++test_transparent_keygen_hit;
+
+    if( test_transparent_keygen_status != PSA_SUCCESS )
+        return( test_transparent_keygen_status );
+
+    if( test_driver_keygen_forced_output != NULL )
+    {
+        if( test_driver_keygen_forced_output_length > key_size )
+            return( PSA_ERROR_BUFFER_TOO_SMALL );
+        memcpy( key, test_driver_keygen_forced_output,
+                test_driver_keygen_forced_output_length );
+        *key_length = test_driver_keygen_forced_output_length;
+        return( PSA_SUCCESS );
+    }
+
+    /* Copied from psa_crypto.c */
+#if defined(MBEDTLS_ECP_C)
+    if ( PSA_KEY_TYPE_IS_ECC( attributes->core.type ) && PSA_KEY_TYPE_IS_KEY_PAIR( attributes->core.type ) )
+    {
+        psa_ecc_family_t curve = PSA_KEY_TYPE_ECC_GET_FAMILY( attributes->core.type );
+        mbedtls_ecp_group_id grp_id =
+            mbedtls_ecc_group_of_psa( curve, PSA_BITS_TO_BYTES( attributes->core.bits ) );
+        const mbedtls_ecp_curve_info *curve_info =
+            mbedtls_ecp_curve_info_from_grp_id( grp_id );
+        mbedtls_ecp_keypair ecp;
+        mbedtls_test_rnd_pseudo_info rnd_info;
+        memset( &rnd_info, 0x5A, sizeof( mbedtls_test_rnd_pseudo_info ) );
+
+        int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+        if( attributes->domain_parameters_size != 0 )
+            return( PSA_ERROR_NOT_SUPPORTED );
+        if( grp_id == MBEDTLS_ECP_DP_NONE || curve_info == NULL )
+            return( PSA_ERROR_NOT_SUPPORTED );
+        if( curve_info->bit_size != attributes->core.bits )
+            return( PSA_ERROR_INVALID_ARGUMENT );
+        mbedtls_ecp_keypair_init( &ecp );
+        ret = mbedtls_ecp_gen_key( grp_id, &ecp,
+                                   &mbedtls_test_rnd_pseudo_rand,
+                                   &rnd_info );
+        if( ret != 0 )
+        {
+            mbedtls_ecp_keypair_free( &ecp );
+            return( mbedtls_to_psa_error( ret ) );
+        }
+
+        /* Make sure to use export representation */
+        size_t bytes = PSA_BITS_TO_BYTES( attributes->core.bits );
+        if( key_size < bytes )
+        {
+            mbedtls_ecp_keypair_free( &ecp );
+            return( PSA_ERROR_BUFFER_TOO_SMALL );
+        }
+        psa_status_t status = mbedtls_to_psa_error(
+            mbedtls_mpi_write_binary( &ecp.d, key, bytes ) );
+
+        if( status == PSA_SUCCESS )
+        {
+            *key_length = bytes;
+        }
+
+        mbedtls_ecp_keypair_free( &ecp );
+        return( status );
+    }
+    else
+#endif /* MBEDTLS_ECP_C */
+    return( PSA_ERROR_NOT_SUPPORTED );
+}
+
+psa_status_t test_opaque_generate_key(
+    const psa_key_attributes_t *attributes,
+    uint8_t *key, size_t key_size, size_t *key_length )
+{
+    (void) attributes;
+    (void) key;
+    (void) key_size;
+    (void) key_length;
+    return( PSA_ERROR_NOT_SUPPORTED );
+}
+
+#endif /* MBEDTLS_PSA_CRYPTO_DRIVERS && MBEDTLS_TEST_HOOKS */