incremental upload refactor

frontend/src/utils.js

@@ -0,0 +1,26 @@
+function 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;
+}
+
+function 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;
+}
+
+module.exports = {
+  ivToStr,
+  strToIv
+};