use Digest::MD5 qw[ md5 ];
sub md5_base32{ 
    join'',map{ 
        ('A'..'Z', 0..5 )[ ord pack 'b5', $_ ] 
    } unpack '(A5)*', unpack'b*', md5( $_[ 0 ] ) 
}

print md5_base32( 'fred' );

XSCAZ54XMU5W0OVYUWYRGZU0RF

##</code><code>##

sub md5_base32_2{ 
    join'', ('A'..'Z', 0..5 )[ 
        unpack 'C*', 
          pack '(b5)*', 
        unpack '(A5)*', 
        unpack 'b*', 
           md5 $_[ 0 ] 
    ] 
}