sub sig{ 
    my $sig = 0; 
    my $n = 0; 
    $sig += ( $_ - 96 ) * ++$n for unpack 'C*', $_[0]; 
    return $sig; 
};;

print $string = join '', map chr( 97+rand( 26) ), 1 .. 10;;
oqqcfuwfco

print $sig = sig( $string );;
654

print $string = join '', map chr( 97+rand( 26) ), 1 .. 10;;
qwfiedngda

print $sig = sig( $string );;
366