用于url重写的htaccess中的base64?

Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-l
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule (?!^infos/)^(.+?)/?$ /dl.php?f=$1 [L,QSA,NC]

this htaccess will transform mydomain.com/somefile to mydomain.com/dl.php?f=somefile But i am wondering if it would be possible to base64-encode the "somefile" part ($1) ? So the value that is passed to $_GET['f'] would be encoded and i would just decode it in my php file