From def490ceca2697bc20c5069467164765ebb3330d Mon Sep 17 00:00:00 2001
From: Claude <claude@webklar.local>
Date: Wed, 30 Sep 2026 20:26:53 +0000
Subject: [PATCH] Preview: GCM-Tag-Laenge fest, Inhalt validiert

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 server/services/previewEnv.js | 12 +++++++++---
 test/previewEnv.test.js       | 22 ++++++++++++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/server/services/previewEnv.js b/server/services/previewEnv.js
index 805cc40..e305113 100644
--- a/server/services/previewEnv.js
+++ b/server/services/previewEnv.js
@@ -15,7 +15,7 @@ export function envKey() {
 
 export function encryptEnv(obj, key) {
   const iv = crypto.randomBytes(12)
-  const cipher = crypto.createCipheriv('aes-256-gcm', key, iv)
+  const cipher = crypto.createCipheriv('aes-256-gcm', key, iv, { authTagLength: 16 })
   const ct = Buffer.concat([cipher.update(JSON.stringify(obj || {}), 'utf8'), cipher.final()])
   const tag = cipher.getAuthTag()
   return ['v1', iv, tag, ct].map((p) => (typeof p === 'string' ? p : p.toString('base64'))).join(':')
@@ -26,10 +26,16 @@ export function decryptEnv(str, key) {
   const parts = String(str).split(':')
   if (parts.length !== 4 || parts[0] !== 'v1') throw new Error('Ungueltiges Variablenformat')
   const [, iv, tag, ct] = parts.map((p, i) => (i === 0 ? p : Buffer.from(p, 'base64')))
-  const decipher = crypto.createDecipheriv('aes-256-gcm', key, iv)
+  if (iv.length !== 12 || tag.length !== 16) throw new Error('Ungueltiges Variablenformat')
+  const decipher = crypto.createDecipheriv('aes-256-gcm', key, iv, { authTagLength: 16 })
   decipher.setAuthTag(tag)
   const plain = Buffer.concat([decipher.update(ct), decipher.final()]).toString('utf8')
-  return JSON.parse(plain)
+  const obj = JSON.parse(plain)
+  if (!obj || typeof obj !== 'object' || Array.isArray(obj)
+    || !Object.values(obj).every((v) => typeof v === 'string')) {
+    throw new Error('Ungueltiges Variablenformat')
+  }
+  return obj
 }
 
 export function envNames(str, key) {
diff --git a/test/previewEnv.test.js b/test/previewEnv.test.js
index 86063c2..d7b827c 100644
--- a/test/previewEnv.test.js
+++ b/test/previewEnv.test.js
@@ -79,3 +79,25 @@ test('maskLog', () => {
   assert.equal(maskLog('', env), '')
   assert.equal(maskLog('text', {}), 'text')
 })
+
+test('gekuerzter Tag, falsche IV-Laenge, manipulierter Ciphertext => Fehler', () => {
+  const p = encryptEnv({ A: 'geheim' }, key).split(':')
+  const b = (i) => Buffer.from(p[i], 'base64')
+  const join = (x) => x.join(':')
+  const short = [...p]; short[2] = b(2).subarray(0, 8).toString('base64')
+  assert.throws(() => decryptEnv(join(short), key))
+  const iv = [...p]; iv[1] = b(1).subarray(0, 8).toString('base64')
+  assert.throws(() => decryptEnv(join(iv), key))
+  const ct = [...p]; const c = b(3); c[0] ^= 1; ct[3] = c.toString('base64')
+  assert.throws(() => decryptEnv(join(ct), key))
+})
+
+test('entschluesselter Inhalt muss Objekt mit String-Werten sein', () => {
+  for (const bad of [['x'], 'text', { A: 1 }, null]) {
+    const iv = crypto.randomBytes(12)
+    const c = crypto.createCipheriv('aes-256-gcm', key, iv, { authTagLength: 16 })
+    const ct = Buffer.concat([c.update(JSON.stringify(bad), 'utf8'), c.final()])
+    const s = ['v1', iv, c.getAuthTag(), ct].map((x) => (typeof x === 'string' ? x : x.toString('base64'))).join(':')
+    assert.throws(() => decryptEnv(s, key))
+  }
+})