Encrypting with Crypto Node.js and decrypt with window.crypto in Service-Worker

Question

Source code: https://github.com/HectorAnadon/Crypto-NodeJS-window.crypto

I am using AES-128-GCM to send an encrypted picture from a node.js server to a service worker (script running in the web browser background) where I am trying to decrypt it. Communication works good because non-encrypted pictures are shown in the web browser.

The PROBLEM is: when I decrypt in the service worker, in the promise cryptoSubtle.decrypt, I get one exception, this is what the console print for me: Decryption error: OperationError: (anonymous function) @ service_worker.js:310

Line 310 in service_worker.js is: console.error("Decryption error: " + err); //Line 310

Do you have any idea about what I am doing wrong? Thank you very much, I really appreciate it.

Here is the encryption code using Crypto Node.js (doc here: https://nodejs.org/api/crypto.html)

// Nodejs encryption with GCM
// Does not work with nodejs v0.10.31
var fs = require('fs');
var crypto = require('crypto');
var algorithm = 'aes-128-gcm';
var key = '3zTvzr3p67VC61jm'; 
// generate a new iv for each encryption
// As this is for testing I always use the same iv
var iv = '60iP0h6vJoEa';


function encrypt(text) {
  var cipher = crypto.createCipheriv(algorithm, key, iv)
  var encrypted = cipher.update(text);
  return encrypted;
}
var text = fs.readFileSync('mustang_encrypted.jpg');
var hw = encrypt(text);

And this is the decryption code in Service worker using window.crypto (doc here: https://developer.mozilla.org/en-US/docs/Web/API/Window/crypto)

//ArrayBuffer of the data we received
function(bodyArrayBuffer) {

    var cryptoObj = crypto;
    var cryptoSubtle = cryptoObj.subtle;

        /*
         *  IMPORT KEY
         */
     string2ArrayBuffer("3zTvzr3p67VC61jm", function (keyBuffer) {          
         console.log("keyBuffer length: " + keyBuffer.byteLength);
         cryptoSubtle.importKey(
            "raw", //can be "jwk" or "raw"
            keyBuffer,
            {   //this is the algorithm options
                name: "AES-GCM",
            },
            false, //whether the key is extractable (i.e. can be used in exportKey)
            ["encrypt", "decrypt"] //can be any combination of "encrypt" and "decrypt"
        ).then(function(key){
            //returns the symmetric key
            /*
             *  DECRYPTION
             */
            string2ArrayBuffer("60iP0h6vJoEa",function (myIV) {
                cryptoSubtle.decrypt(
                        {
                            name: "AES-GCM",
                            iv: myIV, //The initialization vector you used to encrypt
                            tagLength: 128, //The tagLength you used to encrypt
                        },
                        key, //from generateKey or importKey above
                        bodyArrayBuffer //ArrayBuffer of the data
                    )
                    .then(function(decrypted){
                        //returns an ArrayBuffer containing the decrypted data
                        console.log(new Uint8Array(decrypted));
                        //send response
                        var newResponse = new Response(decrypted, init);
                        console.log("Returning \"decrypted\" response!");
                        accept(newResponse);
                    })
                    .catch(function(err){
                        console.error("Decryption error: " + err);  //Line 310
                    });
            });
        })
        .catch(function(err){
            console.error(err);
        });
    });
}

Answer 1

If I remember correctly the window object is not available from within a ServiceWorker, so if you're trying to access window.crypto it will result in an error.