decoder.go

package main

import (
	"bytes"
	"encoding/base64"
	"encoding/binary"
	"fmt"
	"os"
)

func main() {
	var cookie [4]uint32
	cookieStr := os.Args[1]
	data, err := base64.StdEncoding.DecodeString(cookieStr)
	if err != nil {
		panic(err.Error())
	}
	b := []byte(data)
	buf := bytes.NewReader(b)
	err = binary.Read(buf, binary.LittleEndian, &cookie)
	if err != nil {
		panic(err.Error())
	}
	fmt.Printf("%08X%08X%08X%08X\n", cookie[0], cookie[1], cookie[2], cookie[3])

}