add basic daily answer encryption

1 files changed, 51 insertions, 0 deletions

diff --git a/server/index.ts b/server/index.ts
new file mode 100644
index 0000000..bf4cafd
--- /dev/null
+++ b/server/index.ts
@@ -0,0 +1,51 @@
+import express from 'express';
+import path from 'path';
+import crypto from 'crypto';
+import { songs } from '../src/data/songs';
+import { startDate } from '../src/constants/startDate';
+import cors from 'cors';
+
+
+const app = express();
+app.use(cors());
+app.use(express.json());
+
+const PORT = process.env.PORT || 3001;
+const SALT = process.env.HEARDLE_SALT ?? 'changeme';
+
+function getDailyKey(): Buffer {
+  const date = new Date().toISOString().split('T')[0];
+  return crypto.pbkdf2Sync(date, SALT, 100_000, 32, 'sha256');
+}
+
+app.get('/today', (_req, res) => {
+  const msInDay = 86_400_000;
+  const index = Math.floor((Date.now() - startDate.getTime()) / msInDay);
+  const song = songs[index % songs.length];
+
+  const key = getDailyKey();
+  const iv = crypto.randomBytes(12);
+  const cipher = crypto.createCipheriv('aes-256-gcm', key, iv);
+  const encrypted = Buffer.concat([
+    cipher.update(JSON.stringify(song), 'utf8'),
+    cipher.final(),
+  ]);
+  res.json({
+    iv: iv.toString('hex'),
+    tag: cipher.getAuthTag().toString('hex'),
+    data: encrypted.toString('hex'),
+  });
+});
+
+app.get('/songs', (_req, res) => {
+  res.json(songs.map(({ artist, name }) => ({ artist, name })));
+});
+
+if (process.env.NODE_ENV === 'production') {
+  app.use(express.static(path.join(__dirname, '../build')));
+  app.get('*', (_req, res) => {
+    res.sendFile(path.join(__dirname, '../build', 'index.html'));
+  });
+}
+
+app.listen(PORT, () => console.log(`Server running on :${PORT}`));