Add import_key entry point to p256-m driver

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

3rdparty/p256-m/p256-m_driver_entrypoints.c

@@ -24,6 +24,7 @@
 #include "psa/crypto.h"
 #include "psa_crypto_driver_wrappers.h"
 #include <stddef.h>
+#include <string.h>
 
 #if defined(MBEDTLS_P256M_EXAMPLE_DRIVER_ENABLED)
 
@@ -59,6 +60,50 @@ static psa_status_t p256_to_psa_error(int ret)
     }
 }
 
+psa_status_t p256_transparent_import_key(const psa_key_attributes_t *attributes,
+                             const uint8_t *data,
+                             size_t data_length,
+                             uint8_t *key_buffer,
+                             size_t key_buffer_size,
+                             size_t *key_buffer_length,
+                             size_t *bits)
+{
+    /* Check the key size */
+    if (*bits != 0 && *bits != 256) {
+        return PSA_ERROR_NOT_SUPPORTED;
+    }
+
+    /* Validate the key (and its type and size) */
+    psa_key_type_t type = psa_get_key_type(attributes);
+    if (type == PSA_KEY_TYPE_ECC_PUBLIC_KEY(PSA_ECC_FAMILY_SECP_R1)) {
+        if (data_length != 65) {
+            return *bits == 0 ? PSA_ERROR_NOT_SUPPORTED : PSA_ERROR_INVALID_ARGUMENT;
+        }
+        if (p256_validate_pubkey(data + 1) != P256_SUCCESS) {
+            return PSA_ERROR_INVALID_ARGUMENT;
+        }
+    } else if (type == PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1)) {
+        if (data_length != 32) {
+            return *bits == 0 ? PSA_ERROR_NOT_SUPPORTED : PSA_ERROR_INVALID_ARGUMENT;
+        }
+        if (p256_validate_privkey(data) != P256_SUCCESS) {
+            return PSA_ERROR_INVALID_ARGUMENT;
+        }
+    } else {
+        return PSA_ERROR_NOT_SUPPORTED;
+    }
+    *bits = 256;
+
+    /* We only support the export format for input, so just copy. */
+    if (key_buffer_size < data_length) {
+        return PSA_ERROR_BUFFER_TOO_SMALL;
+    }
+    memcpy(key_buffer, data, data_length);
+    *key_buffer_length = data_length;
+
+    return PSA_SUCCESS;
+}
+
 psa_status_t p256_transparent_generate_key(
     const psa_key_attributes_t *attributes,
     uint8_t *key_buffer,

3rdparty/p256-m/p256-m_driver_entrypoints.h

@@ -29,6 +29,39 @@
 
 #include "psa/crypto_types.h"
 
+/** Import SECP256R1 key.
+ *
+ * \param[in]  attributes           The attributes of the key to use for the
+ *                                  operation.
+ * \param[in]  data                 The raw key material. For private keys
+ *                                  this must be a big-endian integer of 32
+ *                                  bytes; for public key this must be an
+ *                                  uncompressed ECPoint (65 bytes).
+ * \param[in]  data_length          The size of the raw key material.
+ * \param[out] key_buffer           The buffer to contain the key data in
+ *                                  output format upon successful return.
+ * \param[in]  key_buffer_size      Size of the \p key_buffer buffer in bytes.
+ * \param[out] key_buffer_length    The length of the data written in \p
+ *                                  key_buffer in bytes.
+ * \param[out] bits                 The bitsize of the key.
+ *
+ * \retval  #PSA_SUCCESS
+ *          Success. Keypair generated and stored in buffer.
+ * \retval  #PSA_ERROR_NOT_SUPPORTED
+ *          The input is not supported by this driver (not SECP256R1).
+ * \retval  #PSA_ERROR_INVALID_ARGUMENT
+ *          The input is invalid.
+ * \retval  #PSA_ERROR_BUFFER_TOO_SMALL
+ *          \p key_buffer_size is too small.
+ */
+psa_status_t p256_transparent_import_key(const psa_key_attributes_t *attributes,
+                             const uint8_t *data,
+                             size_t data_length,
+                             uint8_t *key_buffer,
+                             size_t key_buffer_size,
+                             size_t *key_buffer_length,
+                             size_t *bits);
+
 /** Generate SECP256R1 ECC Key Pair.
  *  Interface function which calls the p256-m key generation function and
  *  places it in the key buffer provided by the caller (mbed TLS) in the