Base 64 encoded string

Could anyone of you please give me some idea to decode base 64 encoded value in ksh?

 
echo "YOURSTRING" | perl -pe 'use MIME::Base64; print MIME::Base64::decode($_);'

There is also the base64 program that's part of the GNU coreutils:

$ base64 --help |grep -F -- -d
  -d, --decode          Decode data.

It works!. Thank you very much