Go: BTCMarkets Authentication Example

main.go

package main

import (
	"crypto/hmac"
	"time"
	"strconv"
	"fmt"
	"net/http"
	"io/ioutil"
	"crypto/sha512"
	"encoding/base64"
	"bytes"
	"os"
)

var (
	publicKey = os.Getenv("BTCM_PUBLIC_KEY")
	privateKey = os.Getenv("BTCM_PRIVATE_KEY")
	apiBase = "https://api.btcmarkets.net"
)

func apiRequest(method, path string, body []byte) ([]byte, error) {

	key, _ := base64.StdEncoding.DecodeString(privateKey)
	mac := hmac.New(sha512.New, []byte(key))

	timestamp := strconv.FormatInt(time.Now().Unix()*1000, 10)

	message := fmt.Sprintf("%s\n%s\n%s", path, timestamp, body)
	mac.Write([]byte(message))
	signature := base64.StdEncoding.EncodeToString(mac.Sum(nil))

	client := &http.Client{}
	req, err := http.NewRequest(method, apiBase+path, bytes.NewReader(body))
	req.Header.Add("Accept", "application/json")
	req.Header.Add("Accept-Charset", "UTF-8")
	req.Header.Add("Content-Type", "application/json")
	req.Header.Add("apiKey", publicKey)
	req.Header.Add("timestamp", timestamp)
	req.Header.Add("signature", signature)
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	} else {
		defer resp.Body.Close()
		data, err := ioutil.ReadAll(resp.Body)
		return data, err
	}
}

func main() {

	data, err := apiRequest("GET", "/account/balance", nil)
	if err != nil {
		fmt.Printf("The HTTP request failed with error %s\n", err)
	} else {
		fmt.Println(string(data))
	}
}