Golang

// signature, attach this one in header
sig := signature.Sign("APISecret", params)

// caller function
func Sign(secret string, payload map[string]interface{}) string {
   sig := xsig.Sign([]byte(secret), payload)
   dst := make([]byte, hex.EncodedLen(len(sig)))
   hex.Encode(dst, sig)
   return string(dst)
}

//signature signer
import (
   "crypto/hmac"
   "crypto/sha512"
   "fmt"
   "sort"

   "github.com/sirupsen/logrus"
)

func ConstructQueryString(params map[string]interface{}) string {
   return constructQueryStringWithPrefix(params, "")
}

func Sign(secret []byte, params map[string]interface{}) []byte {
   qs := ConstructQueryString(params)
   mac := hmac.New(sha512.New, secret)
   mac.Write([]byte(qs))
   return mac.Sum(nil)
}

func Verify(secret []byte, params map[string]interface{}, signature []byte) bool {
   return hmac.Equal(Sign(secret, params), signature)
}

func constructQueryStringWithPrefix(params map[string]interface{}, prefix string) string {
   var keys []string

   for k, _ := range params {
      keys = append(keys, k)
   }

   sort.Strings(keys)

   var qs string

   for i, k := range keys {
      v := params[k]

      if nestedParams, ok := v.(map[string]interface{}); ok {
         qs += constructQueryStringWithPrefix(nestedParams, k)
      } else if array, ok := v.([]interface{}); ok {
         nestedMap := map[string]interface{}{}
         for i, v := range array {
            nestedMap[fmt.Sprintf("%d", i)] = v
         }
         qs += constructQueryStringWithPrefix(nestedMap, k)
      } else {
         if prefix == "" {
            if _, ok := v.(float64); ok {
               qs += fmt.Sprintf("%s=%.f", k, v)
            } else {
               qs += fmt.Sprintf("%s=%v", k, v)
            }
         } else {
            if _, ok := v.(float64); ok {
               qs += fmt.Sprintf("%s[%s]=%.f", prefix, k, v)
            } else {
               qs += fmt.Sprintf("%s[%s]=%v", prefix, k, v)
            }
         }
      }

      if i != len(keys)-1 {
         qs += "&"
      }
   }

   return qs
}