golang sha1 signature

package models

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

func Sha1(query string, pri_key string) string {
    key := []byte(pri_key)
    mac := hmac.New(sha1.New, key)
    mac.Write([]byte(query))
    query = base64.StdEncoding.EncodeToString(mac.Sum(nil))
    query = url.QueryEscape(query)
    return query
}