my $octets= encode("utf16", '1234');

$octets= substr($octets,2);

for my $i (0..(length($octets)/2-1)) {
    my $n= substr($octets,$i*2,1);
    substr( $octets,$i*2,1)= substr($octets,$i*2+1,1);
    substr($octets,$i*2+1,1)=$n;
}

print sha1_base64($octets);