Update safety number change warning dialog

ts/util/safetyNumber.ts

@@ -0,0 +1,58 @@
+import { ConversationType } from '../state/ducks/conversations';
+
+export async function generateSecurityNumber(
+  ourNumber: string,
+  ourKey: ArrayBuffer,
+  theirNumber: string,
+  theirKey: ArrayBuffer
+): Promise<string> {
+  return new window.libsignal.FingerprintGenerator(5200).createFor(
+    ourNumber,
+    ourKey,
+    theirNumber,
+    theirKey
+  );
+}
+
+export function getPlaceholder(): string {
+  return Array.from(Array(12))
+    .map(() => 'XXXXX')
+    .join(' ');
+}
+
+export async function generateSecurityNumberBlock(
+  contact: ConversationType
+): Promise<Array<string>> {
+  const ourNumber = window.textsecure.storage.user.getNumber();
+  const ourUuid = window.textsecure.storage.user.getUuid();
+
+  const us = window.textsecure.storage.protocol.getIdentityRecord(
+    ourUuid || ourNumber
+  );
+  const ourKey = us ? us.publicKey : null;
+
+  const them = window.textsecure.storage.protocol.getIdentityRecord(contact.id);
+  const theirKey = them ? them.publicKey : null;
+
+  if (!ourKey) {
+    throw new Error('Could not load our key');
+  }
+
+  if (!theirKey) {
+    throw new Error('Could not load their key');
+  }
+
+  const securityNumber = await generateSecurityNumber(
+    ourNumber,
+    ourKey,
+    contact.e164,
+    theirKey
+  );
+
+  const chunks = [];
+  for (let i = 0; i < securityNumber.length; i += 5) {
+    chunks.push(securityNumber.substring(i, i + 5));
+  }
+
+  return chunks;
+}