How to Encrypt and Password Protect a PDF using Go

Reliable document security is one of the chief advantages of PDF format. Encryption and password protection features make it possible to keep viewership of a document static between a trusted group of peers, eliminating the risk of unwanted parties appending or revising the document. With our free-to-use PDF Encryption & Password Protection API, you can programmatically set custom permissions for dozens of PDF documents (one API call per document) in a one-step process that involves setting a user password, owner password, and encryption key length (values include 128-bit RC4 encryption and 256-bit AES encryption; the latter is the default setting).

Taking advantage of this API is easy; all you need to do is copy & paste the complementary Go code examples provided below and register a free account on our website to get a free-tier Cloudmersive API key (this key will yield a limit of 800 API calls per month & no additional commitments).

To use this API, include the below code examples in your file and fill the required header fields as directed by the code comments:

package main

import (
     "fmt"
     "bytes"
     "mime/multipart"
     "os"
     "path/filepath"
     "io"
     "net/http"
     "io/ioutil"
)

func main() {

     url := "https://api.cloudmersive.com/convert/edit/pdf/encrypt"
     method := "POST"

     payload := &bytes.Buffer{}
     writer := multipart.NewWriter(payload)
     file, errFile1 := os.Open("/path/to/file")
     defer file.Close()
     part1,
         errFile1 := writer.CreateFormFile("inputFile",filepath.Base("/path/to/file"))
     _, errFile1 = io.Copy(part1, file)
     if errFile1 != nil {
          fmt.Println(errFile1)
          return
     }
     err := writer.Close()
     if err != nil {
          fmt.Println(err)
          return
     }


     client := &http.Client {
     }
     req, err := http.NewRequest(method, url, payload)

     if err != nil {
          fmt.Println(err)
          return
     }
     req.Header.Add("userPassword", "<string>")
     req.Header.Add("ownerPassword", "<string>")
     req.Header.Add("encryptionKeyLength", "<string>")
     req.Header.Add("Content-Type", "multipart/form-data")
     req.Header.Add("Apikey", "YOUR-API-KEY-HERE")

     req.Header.Set("Content-Type", writer.FormDataContentType())
     res, err := client.Do(req)
     if err != nil {
          fmt.Println(err)
          return
     }
     defer res.Body.Close()

     body, err := ioutil.ReadAll(res.Body)
     if err != nil {
          fmt.Println(err)
          return
     }
     fmt.Println(string(body))
}

Simple as that — you’re all done.