Payu Order Hash with HMAC MD5 https://payuturkiye.github.io/PayU-Turkiye-Entegrasyon-Dokumani/#yanit-parametreleri

payu.go

package main

import (
	"crypto/hmac"
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"sort"
	"strconv"
)

func main() {

	mm := map[string]string{
		"BACK_REF":             "http://www.backref.com.tr",
		"BILL_ADDRESS":         "Birinci Adres satır",
		"BILL_ADDRESS2":        "İkinci Adres satırı",
		"BILL_CITY":            "ISTANBUL",
		"BILL_COUNTRYCODE":     "TR",
		"BILL_EMAIL":           "[email protected]",
		"BILL_FAX":             "02129003711",
		"BILL_FNAME":           "Ad",
		"BILL_LNAME":           "Soyad",
		"BILL_PHONE":           "02129003711",
		"BILL_STATE":           "Ayazağa",
		"BILL_ZIPCODE":         "34000",
		"CC_CVV":               "000",
		"CC_NUMBER":            "4355084355084358",
		"CC_OWNER":             "Ad Soyad",
		"CLIENT_IP":            "127.0.0.1",
		"DELIVERY_ADDRESS":     "Birinci Adres satırı",
		"DELIVERY_ADDRESS2":    "İkinci Adres satırı",
		"DELIVERY_CITY":        "ISTANBUL",
		"DELIVERY_COMPANY":     "PayU Ödeme Kuruluşu A.Ş.",
		"DELIVERY_COUNTRYCODE": "Ayazağa",
		"DELIVERY_EMAIL":       "[email protected]",
		"DELIVERY_FNAME":       "Ad",
		"DELIVERY_LNAME":       "Soyad",
		"DELIVERY_PHONE":       "02129003711",
		"DELIVERY_STATE":       "TR",
		"DELIVERY_ZIPCODE":     "34000",
		"EXP_MONTH":            "12",
		"EXP_YEAR":             "2018",
		"LANGUAGE":             "TR",
		"MERCHANT":             "OPU_TEST",
		"ORDER_DATE":           "2017-10-04 11:10:23",
		"ORDER_PCODE0":         "Test Kodu",
		"ORDER_PCODE1":         "Test Kodu-2",
		"ORDER_PINFO0":         "Test Açıklaması",
		"ORDER_PINFO1":         "Test Açıklaması-2",
		"ORDER_PNAME0":         "Test Ürünü",
		"ORDER_PNAME1":         "Test Ürünü-2",
		"ORDER_PRICE0":         "5",
		"ORDER_PRICE1":         "15",
		"ORDER_PRICE_TYPE0":    "NET",
		"ORDER_PRICE_TYPE1":    "GROSS",
		"ORDER_QTY0":           "1",
		"ORDER_QTY1":           "3",
		"ORDER_REF":            "3245",
		"ORDER_SHIPPING":       "5",
		"ORDER_VAT0":           "18",
		"ORDER_VAT1":           "24",
		"PAY_METHOD":           "CCVISAMC",
		"PRICES_CURRENCY":      "TRY",
	}

	keys := make([]string, 0, len(mm))
	for k := range mm {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	resp := ""
	for _, k := range keys {
		resp += strconv.Itoa(len(mm[k]))
		resp += mm[k]
	}
	fmt.Println(resp)

	// resp olusturdugumuz string

	key := []byte("secret key buraya gelecek")
	sig := hmac.New(md5.New, key)
	sig.Write([]byte(resp))

	fmt.Println("Response hex! -> ", hex.EncodeToString(sig.Sum(nil)))

}