rename "encryption key management plugin" to "encryption plugin"

because it's going to do more than just key management

include/mysql/plugin_encryption.h

@@ -0,0 +1,73 @@
+#ifndef MYSQL_PLUGIN_ENCRYPTION_INCLUDED
+/* Copyright (C) 2014 Sergei Golubchik and MariaDB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+/**
+  @file
+
+  Encryption Plugin API.
+
+  This file defines the API for server plugins that manage encryption
+  keys for MariaDB on-disk data encryption.
+*/
+
+#define MYSQL_PLUGIN_ENCRYPTION_INCLUDED
+
+#include <mysql/plugin.h>
+
+#define MariaDB_ENCRYPTION_INTERFACE_VERSION 0x0200
+
+#define BAD_ENCRYPTION_KEY_VERSION (~(unsigned int)0)
+#define KEY_BUFFER_TOO_SMALL       (100)
+
+/**
+  Encryption plugin descriptor
+*/
+struct st_mariadb_encryption
+{
+  int interface_version;                        /**< version plugin uses */
+
+  /**
+    function returning latest key version.
+
+    @return a version or BAD_ENCRYPTION_KEY_VERSION to indicate an error.
+  */
+  unsigned int (*get_latest_key_version)();
+
+  /**
+    function returning a key for a key version
+
+    @param version      the requested key version
+    @param key          the key will be stored there. Can be NULL -
+                        in which case no key will be returned
+    @param key_length   in: key buffer size
+                        out: the actual length of the key
+
+    This method can be used to query the key length - the required
+    buffer size - by passing key==NULL.
+
+    If the buffer size is less than the key length the content of the
+    key buffer is undefined (the plugin is free to partially fill it with
+    the key data or leave it untouched).
+
+    @return 0 on success, or
+            BAD_ENCRYPTION_KEY_VERSION, KEY_BUFFER_TOO_SMALL,
+            or any other non-zero number for errors
+  */
+  unsigned int (*get_key)(unsigned int version, unsigned char *key,
+                          unsigned int *key_length);
+};
+#endif
+