mod_rewrite and URLencoded strings

Had a rewrite rule to direct from a non- 'www' host to the www host with a CGI variable, example:

<VirtualHost ....>
.
.
.
ServerName ThIsHoSt.domain.com
RewriteEngine on
RewriteRule /.* http://www.domain.com/index.cgi?origin=ThIsHoSt
</VirtualHost>

this worked fine.
The powers that be deemed it necessary to encrypt the CGI variable. The encryption led the string ("ThIsHoSt") to become something quite non-url friendly, it became: "&9f#' RM934%S" (not including quotes).

RewriteRule /.* http://www.domain.com/index.cgi?origin=&9f#' RM934%S

the above wasn't going to fly, so I URL encoded the encrypted string. Now it no longer had any special chars. Only thing is, Rewrite treats `%'s as special chars, so stuff like %20, %2E, etc... were sucked into Rewrite, and barfed out. This made the CGI variable completely useless, as it could not be decoded when it has been through a blender.

Went the documentation, and searched the web and newsgroups, and did not find a solution to my seemingly unique problem.

Appreciate any help.

Jay