gistfile1.go

package main

import (
	"bytes"
	"crypto/hmac"
	"crypto/sha1"
	"encoding/base64"
	"fmt"
	"net/url"
	"sort"
)

const (
	consumerSecret   = "kAcSOqF21Fu85e7zjz7ZN2U4ZRhfV3WpwPAoE3Z7kBw"
	oauthTokenSecret = "LswwdoUaIvS8ltyTt5jkRh4J50vUPVVHtR2YPi5kE"
)

type RestMethod struct {
	Url    string
	Method string
	Params map[string]string
}

func main() {
	params := make(map[string]string)
	params["oauth_consumer_key"] = "xvz1evFS4wEEPTGEFPHBog"
	params["oauth_version"] = "1.0"
	params["include_entities"] = "true"
	params["oauth_nonce"] = "kYjzVBB8Y0ZFabxSWbWovY3uYSQ2pTgmZeNu2VS4cg"
	params["oauth_token"] = "370773112-GmHxMAgYyLbNEtIKZeRNFsMKPR9EyMZeS9weJAEb"
	params["oauth_signature_method"] = "HMAC-SHA1"
	params["oauth_timestamp"] = "1318622958"

	method := RestMethod{
		Url:    "https://api.twitter.com/1/statuses/update.json",
		Method: "POST",
		Params: params,
	}

	str := generateSignatureBase(method)
	fmt.Println(str)

	sig := generateOAuthSignature(str)
	fmt.Println(sig)
}

func generateOAuthSignature(signatureBase string) string {
	signingKey := fmt.Sprintf("%s&%s", consumerSecret, oauthTokenSecret)

	h := hmac.New(sha1.New, []byte(signingKey))
	h.Write([]byte(signatureBase))

	return base64.StdEncoding.EncodeToString(h.Sum(nil))
}

func generateSignatureBase(m RestMethod) string {
	var buffer bytes.Buffer

	// write method and url to buffer
	buffer.WriteString(m.Method + "&")
	buffer.WriteString(encode(m.Url) + "&")

	// sort map keys
	sortedKeys := sortMapKeys(m.Params)

	// write each parameter to buffer
	for _, v := range sortedKeys {
		buffer.WriteString(encode(fmt.Sprintf("%s=%s&", v, m.Params[v])))
	}

	// turn buffer into string
	output := buffer.String()

	// remove trailing &
	return output[:len(output)-1]
}

func sortMapKeys(m map[string]string) []string {
	keys := make([]string, len(m))
	i := 0
	for k, _ := range m {
		keys[i] = k
		i++
	}
	sort.Strings(keys)
	return keys
}

// wrapper for url.QueryEscape
func encode(str string) string {
	return url.QueryEscape(str)
}