Node.js qpdf Library Example to Encrypt PDF Documents With Password Using Child Process Module

Welcome folks today in this blog post we will be encrypting pdf documents with password using the qpdf library in command line using child process. All the full source code of the application is shown below.

Get Started

In order to get started you need to install the qpdf library globally inside your system on the command line

npm i -g qpdf

After that you need to use this library using the below command as shown below

qpdf --encrypt user-password key-length flags -- source-file-path destination-file-path

1	qpdf --encrypt user-password key-length flags -- source-file-path destination-file-path

As you can see we are using the above command here you need to replace the path of the input pdf file and output pdf file. And here you need to replace the password you need to encrypt. This command will translate into as shown below

qpdf --encrypt test 40 sample.pdf encrypted.pdf

And now you can make the index.js file inside the node.js project using the child_process() module as shown below

index.js

let exec = require('child_process').exec

let cmd = "qpdf --encrypt test 40 sample.pdf encrypted.pdf"

exec(cmd,(err) => {
    if(err){
        console.log(err)
    }
    else{
        console.log("PDF encrypted")
    }
})

let exec = require('child_process').exec

let cmd = "qpdf --encrypt test 40 sample.pdf encrypted.pdf"

exec(cmd,(err) => {

if(err){

console.log(err)

}

else{

console.log("PDF encrypted")

}

})