Maybe not the answer you want, but I would use Juerds snippet for this.

Semi-OT random ramblings: I took Juerds snippet and modified it into two new functions: base64_encode_struct and base64_decode_struct. Instead of chomp:ing the data I encoded/decoded it with MIME::Base64. Useful if you have a complex data structure that you want to use with XML::Simple but you want to Base64-encode the data (not the tags).