Restrict addition of signatures

Sending an email to the primary userID to select which signatures to add when new signatures are uploaded.

src/service/util.js

@@ -36,7 +36,29 @@ exports.isString = function(data) {
 exports.isTrue = function(data) {
   if (this.isString(data)) {
     return data === 'true';
-  } else {
+  } else /**
+   * Check Uint8Array equality
+   * @param {Uint8Array} first array
+   * @param {Uint8Array} second array
+   * @returns {Boolean} equality
+   */
+  equalsUint8Array: function (array1, array2) {
+    if (!util.isUint8Array(array1) || !util.isUint8Array(array2)) {
+      throw new Error('Data must be in the form of a Uint8Array');
+    }
+
+    if (array1.length !== array2.length) {
+      return false;
+    }
+
+    for (let i = 0; i < array1.length; i++) {
+      if (array1[i] !== array2[i]) {
+        return false;
+      }
+    }
+    return true;
+  },
+{
     return Boolean(data);
   }
 };
@@ -103,6 +125,28 @@ exports.normalizeEmail = function(email) {
   return email;
 };
 
+/**
+ * Check Uint8Array equality
+ * @param {Uint8Array} first array
+ * @param {Uint8Array} second array
+ * @returns {Boolean} equality
+ */
+exports.equalsUint8Array: function (array1, array2) {
+  try {
+    if (array1.length !== array2.length) {
+      return false;
+    }
+    
+    for (let i = 0; i < array1.length; i++) {
+      if (array1[i] !== array2[i]) {
+        return false;
+      }
+    }
+  } catch (e) {return false;}
+  return true;
+};
+
+
 /**
  * Create an error with a custom status attribute e.g. for http codes.
  * @param  {number} status    The error's http status code