tsr.go

package main

import (
        "bytes"
        "encoding/json"
        "fmt"
        "io/ioutil"
        "log"
        "net/http"
        "strings"

        tsp "github.com/digitorus/timestamp"
)

func main() {

        tsreq, err := tsp.CreateRequest(strings.NewReader("Content to by time-stamped"), nil)
        if err != nil {
                panic(err)
        }

        req, err := http.NewRequest("POST", "http://timestamp.digicert.com/", bytes.NewReader(tsreq))
        if err != nil {
                log.Fatal(err)
        }
        req.Header.Set("Content-Type", "application/timestamp-query")

        cli := &http.Client{}
        resp, err := cli.Do(req)
        if err != nil || resp == nil {
                log.Fatal(err)
        }
        defer resp.Body.Close()
        body, err := ioutil.ReadAll(resp.Body)
        if err != nil {
                log.Fatal(err)
        }
        if resp.StatusCode != http.StatusOK {
                log.Fatalf("%s %s", resp.Status, body)
        }

        tsresp, err := tsp.ParseResponse(body)
        if err != nil {
                log.Fatal(err)
        }

        tsresp.Certificates = nil
        jsonTs, err := json.MarshalIndent(tsresp, "", "    ")
        if err != nil {
                log.Fatal(err)
        }
        fmt.Printf("%s\n", jsonTs)
}

$ go run get_timestamp.go

{
    "HashAlgorithm": 5,
    "HashedMessage": "YmM8MjIRVFSWPOZB5QlcSKhdvskToIMyrThYa5EKOyc=",
    "Time": "2018-06-27T13:11:57Z",
    "Accuracy": 0,
    "SerialNumber": 142820471890552379720677726973857460188,
    "Certificates": null,
    "Extensions": null,
    "ExtraExtensions": null
}