current post with current author

A compacted version that does not load the globals yet calls upon them directly.

if(
    is_user_logged_in() and // Force user validation... STUFF
    !empty($GLOBALS['post']) and // Check if a $post exists in globals
    !empty($GLOBALS['current_user']) and // Check if current_user exists in globals
    ($GLOBALS['current_user']->ID == $GLOBALS['post']->post_author) // Match User IDs
){
    // This is your Author speaking, use the Force!
}

Regards.