file uploader using webworker - worker.js

importScripts('crypto-js.js'); 
 
/** 
 * 
 * @param binaryText file binary text 
 * @param key password to encrypt 
 * @return {string} 
 */ 
 
function _base64ToBlob(b64Data, contentType, sliceSize) { 
  contentType = contentType || ''; 
  sliceSize = sliceSize || 512; 
 
  let byteCharacters = atob(b64Data.split(',')[1]); 
  let byteArrays = []; 
 
  for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) { 
    let slice = byteCharacters.slice(offset, offset + sliceSize); 
 
    let byteNumbers = new Array(slice.length); 
    for (let i = 0; i < slice.length; i++) { 
      byteNumbers[i] = slice.charCodeAt(i); 
    } 
 
    let byteArray = new Uint8Array(byteNumbers); 
 
    byteArrays.push(byteArray); 
  } 
 
  let blob = new Blob(byteArrays, {type: contentType}); 
  return blob; 
} 
 
function encryptBase64(base64, key) { 
 
  return btoa(CryptoJS.AES.encrypt(base64, key).toString()); 
 
} 
 
 
function encryptedBase64ToBlob(encryptedBase64, key, contentType) { 
  return _base64ToBlob(CryptoJS.AES.decrypt(encryptedBase64, key).toString(CryptoJS.enc.Utf8), contentType); 
} 
 
onmessage = function (e) { 
 
  const data = e.data; 
 
  const key = data.actionKey; 
 
  let response; 
 
  switch (data.action) { 
    case 'encryptBase64': 
      response = { 
        type: 'encryptBase64', 
        result: encryptBase64(data.payload.base64, data.payload.key), 
        key 
      }; 
      break; 
    case 'encryptedBase64ToBlob': 
      response = { 
        type: 'encryptedBase64ToBlob', 
        result: encryptedBase64ToBlob(data.payload.encryptedBase64, data.payload.key, data.payload.contentType), 
        key 
      }; 
 
      break; 
  } 
 
 
  postMessage(response); 
 
 
};