psa: Add get/set domain parameters

DSA and static DH need extra domain parameters. Instead of passing these
in with the keys themselves, add get and set functions to set and
retrieve this information about keys.

Author: Patater

include/psa/crypto.h

@@ -369,6 +369,26 @@ psa_status_t psa_get_key_information(psa_key_handle_t handle,
                                      psa_key_type_t *type,
                                      size_t *bits);
 
+/**
+ *
+ * Format for the domain parameters varies by the key type.
+ * Must call before import key. If you want, you can call before generate key
+ * or use extra to pass the domain parameters.
+ *
+ * Bad state error if called after imported or generated key already.
+ */
+psa_status_t psa_set_key_domain_parameters(uint8_t *data,
+                                           size_t data_size,
+                                           size_t data_length);
+
+/**
+ *
+ * It gets the domain parameters. 8-)
+ */
+psa_status_t psa_get_key_domain_parameters(uint8_t *data,
+                                           size_t data_size,
+                                           size_t *data_length);
+
 /**
  * \brief Export a key in binary format.
  *

library/psa_crypto.c

@@ -722,7 +722,7 @@ psa_status_t psa_import_key_into_slot( psa_key_slot_t *slot,
 }
 
 /* Retrieve an empty key slot (slot with no key data, but possibly
- * with some metadata such as a policy). */
+ * with some metadata such as a policy or domain parameters). */
 static psa_status_t psa_get_empty_key_slot( psa_key_handle_t handle,
                                             psa_key_slot_t **p_slot )
 {