sub md5_decrypt
{
    my $iv_len = 16;
    my $enc_text = decode_base64(shift);
    my $password = shift;
    my $n = length($enc_text);
    my $i = $iv_len;
    my $plain_text;
    my $iv = substr($password ^ substr($enc_text,0,length($password)), 0, 512);
    my $x;

    while ($i < $n) {
        my $block = substr($enc_text, $i, 16);
        $plain_text .= $block ^ pack('H*', md5_hex($iv));
        $iv = substr($block . $iv, 0, length($password)) ^ $password;
        $i += 16;
    }
    #$plain_text =~ s/\x13\x00*$//;
    return $plain_text;
}