From d0832c6c0a6e421e2eb221f5e83951001f3b70a1 Mon Sep 17 00:00:00 2001
From: Rob Walch <robwalch@users.noreply.github.com>
Date: Fri, 24 May 2024 11:50:35 -0700
Subject: [PATCH] Fix JS AES fallback when browserCrypto.subtle returns
 undefined (rather than null) (#6446)

---
 src/crypt/decrypter.ts    | 19 +++++++++++++------
 src/crypt/fast-aes-key.ts |  4 ++--
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/crypt/decrypter.ts b/src/crypt/decrypter.ts
index 299dd23b64a..a3f988d1c5f 100644
--- a/src/crypt/decrypter.ts
+++ b/src/crypt/decrypter.ts
@@ -38,7 +38,7 @@ export default class Decrypter {
         /* no-op */
       }
     }
-    this.useSoftware = this.subtle === null;
+    this.useSoftware = !this.subtle;
   }
 
   destroy() {
@@ -155,20 +155,22 @@ export default class Decrypter {
     iv: ArrayBuffer,
     aesMode: DecrypterAesMode,
   ): Promise<ArrayBuffer> {
-    const subtle = this.subtle;
     if (this.key !== key || !this.fastAesKey) {
+      if (!this.subtle) {
+        return Promise.resolve(this.onWebCryptoError(data, key, iv, aesMode));
+      }
       this.key = key;
-      this.fastAesKey = new FastAESKey(subtle, key, aesMode);
+      this.fastAesKey = new FastAESKey(this.subtle, key, aesMode);
     }
     return this.fastAesKey
       .expandKey()
       .then((aesKey: CryptoKey) => {
         // decrypt using web crypto
-        if (!subtle) {
+        if (!this.subtle) {
           return Promise.reject(new Error('web crypto not initialized'));
         }
         this.logOnce('WebCrypto AES decrypt');
-        const crypto = new AESCrypto(subtle, new Uint8Array(iv), aesMode);
+        const crypto = new AESCrypto(this.subtle, new Uint8Array(iv), aesMode);
         return crypto.decrypt(data.buffer, aesKey);
       })
       .catch((err) => {
@@ -180,7 +182,12 @@ export default class Decrypter {
       });
   }
 
-  private onWebCryptoError(data, key, iv, aesMode): ArrayBuffer | never {
+  private onWebCryptoError(
+    data: Uint8Array,
+    key: ArrayBuffer,
+    iv: ArrayBuffer,
+    aesMode: DecrypterAesMode,
+  ): ArrayBuffer | never {
     const enableSoftwareAES = this.enableSoftwareAES;
     if (enableSoftwareAES) {
       this.useSoftware = true;
diff --git a/src/crypt/fast-aes-key.ts b/src/crypt/fast-aes-key.ts
index 277baf26419..8312f66aec3 100644
--- a/src/crypt/fast-aes-key.ts
+++ b/src/crypt/fast-aes-key.ts
@@ -1,11 +1,11 @@
 import { DecrypterAesMode } from './decrypter-aes-mode';
 
 export default class FastAESKey {
-  private subtle: any;
+  private subtle: SubtleCrypto;
   private key: ArrayBuffer;
   private aesMode: DecrypterAesMode;
 
-  constructor(subtle, key, aesMode: DecrypterAesMode) {
+  constructor(subtle: SubtleCrypto, key, aesMode: DecrypterAesMode) {
     this.subtle = subtle;
     this.key = key;
     this.aesMode = aesMode;