send/frontend/src/upload.js

const EventEmitter = require('events');
const UIWrapper = require('./file').UIWrapper;

let onChange = (event) => {
  let file = event.target.files[0];
  let reader = new FileReader();
  reader.readAsArrayBuffer(file);

  let random_iv = window.crypto.getRandomValues(new Uint8Array(16));
  let hex = ivToStr(random_iv);

  reader.onload = function(event) {
    let self = this;
    window.crypto.subtle.generateKey({
      name: "AES-CBC",
      length: 128 
    },
    true,
    ["encrypt", "decrypt"])
    .then((key) => {
      let arrayBuffer = self.result;
      let array = new Uint8Array(arrayBuffer);

      window.crypto.subtle.encrypt({
        name: "AES-CBC",
        iv: random_iv },
        key,
        array)
      .then(uploadFile.bind(null, file, hex, key))
      .catch((err) => console.error(err));

    }).catch((err) => console.error(err));   
  };
}

window.onChange = onChange;

let uploadFile = (file, hex, key, encrypted) => {
  let dataView = new DataView(encrypted);
  let blob = new Blob([dataView], { type: file.type });
  
  let fd = new FormData();
  fd.append("fname", file.name);
  fd.append("data", blob, file.name);

  let xhr = new XMLHttpRequest();
  xhr.open("post", "/upload/" + hex, true);

  let listelem = setupUI();
  listelem.emit('name', file.name);
  xhr.upload.addEventListener("progress", updateProgress.bind(null, listelem));

  xhr.onreadystatechange = () => { 
    if (xhr.readyState == XMLHttpRequest.DONE) {
      window.crypto.subtle.exportKey("jwk", key).then((keydata) => {
        localStorage.setItem(hex, xhr.responseText);

        listelem.emit('link', "http://localhost:3000/download/" + hex + "/#" + keydata.k)

        console.log("Share this link with a friend: http://localhost:3000/download/" + hex + "/#" + keydata.k);
      })
    }
  };

  xhr.send(fd);
}

let updateProgress = (UIelem, e) => {
  if (e.lengthComputable) {
    let percentComplete = Math.floor((e.loaded / e.total) * 100);
    UIelem.emit('progress', "Progress: " + percentComplete + "%")

    if (percentComplete === 100) {
      let btn = document.createElement("button");
      btn.innerText = "Delete from server";
      btn.addEventListener("click", () => {
        let segments = UIelem.link.innerText.split("/");
        let key = segments[segments.length - 2];

        let xhr = new XMLHttpRequest();
        xhr.open("post", "/delete/" + key, true);
        xhr.setRequestHeader("Content-Type", "application/json");
        if (!localStorage.getItem(key)) return;

        xhr.send(JSON.stringify({delete_token: localStorage.getItem(key)}));

        xhr.onreadystatechange = () => {
          if (xhr.readyState === XMLHttpRequest.DONE) {
            document.getElementById("uploaded_files").removeChild(UIelem.li);
            localStorage.removeItem(key);
          }

          if (xhr.status === 200) {
            console.log("The file was successfully deleted.");
          } else {
            console.log("The file has expired, or has already been deleted.");
          }
        }
        
      });
      UIelem.li.appendChild(btn);
    }
  }
}

let setupUI = () => {
  let li = document.createElement("li");
  let name = document.createElement("p");
  li.appendChild(name);
  
  let link = document.createElement("a");
  li.appendChild(link);

  let progress = document.createElement("p");
  li.appendChild(progress);

  document.getElementById("uploaded_files").appendChild(li);

  return new UIWrapper(li, name, link, progress);
}

let ivToStr = (iv) => {
  let hexStr = "";
  for (let i in iv) {
    if (iv[i] < 16) {
      hexStr += "0" + iv[i].toString(16);
    } else {
      hexStr += iv[i].toString(16);
    }
  }
  window.hexStr = hexStr;
  return hexStr;
}

let strToIv = (str) => {
  let iv = new Uint8Array(16);
  for (let i = 0; i < str.length; i += 2) {
    iv[i/2] = parseInt((str.charAt(i) + str.charAt(i + 1)), 16);
  }

  return iv;
}