php - Came across base64 while checking theme coding. Is this code malicious or not? -

i checking code of wordpress theme , came across strings containing base64, not expert heard malicious. can glance on these lines of code , tell if malicious or not?

<div class="tiepanel-item">     <h3><?php _e( 'export', 'tie' ) ?></h3>     <div class="option-item">         <textarea style="width:100%" rows="7"><?php echo $currentsettings = base64_encode( serialize( $current_options )); ?></textarea>     </div> </div> <div class="tiepanel-item">     <h3><?php _e( 'import', 'tie' ) ?></h3>     <div class="option-item">         <textarea id="tie_import" name="tie_import" style="width:100%" rows="7"></textarea>     </div> </div> 

and

add_action('wp_ajax_test_theme_data_save', 'tie_save_ajax'); function tie_save_ajax()  {     check_ajax_referer('test-theme-data', 'security');     $data = $_post;     $refresh = 1;      if( !empty( $data['tie_import'] ) )     {         $refresh = 2;         $data = unserialize(base64_decode( $data['tie_import'] ));         array_walk_recursive( $data , 'tie_clean_imported_options');     }      tie_save_settings ($data , $refresh ); } 

it's import/export settings functionality of theme. base 64 used encode serialized string of theme options - it's common practice prevent original data getting corrupted (base 64 converts text in ascii safe in database collation).