Use Widevine KEYID or parse Playready when level keys are present

Update keyUriToKeyIdMap set after KEY_LOADING

Author: robwalch

api-extractor/report/hls.js.api.md

@@ -3361,7 +3361,9 @@ export class LevelKey implements DecryptData {
     // (undocumented)
     readonly encrypted: boolean;
     // (undocumented)
-    getDecryptData(sn: number | 'initSegment'): LevelKey | null;
+    getDecryptData(sn: number | 'initSegment', levelKeys?: {
+        [key: string]: LevelKey | undefined;
+    }): LevelKey | null;
     // (undocumented)
     readonly isCommonEncryption: boolean;
     // (undocumented)

src/loader/fragment.ts

@@ -273,7 +273,7 @@ export class Fragment extends BaseSegment {
           const levelKey = (this._decryptdata =
             this.levelkeys[keyFormats[0]] || null);
           if (levelKey) {
-            return levelKey.getDecryptData(this.sn);
+            return levelKey.getDecryptData(this.sn, this.levelkeys);
           }
         } else {
           // Multiple keys. key-loader to call Fragment.setKeyFormat based on selected key-system.
@@ -364,10 +364,11 @@ export class Fragment extends BaseSegment {
   }
 
   setKeyFormat(keyFormat: KeySystemFormats) {
-    if (this.levelkeys) {
-      const key = this.levelkeys[keyFormat];
+    const levelkeys = this.levelkeys;
+    if (levelkeys) {
+      const key = levelkeys[keyFormat];
       if (key && !this._decryptdata) {
-        this._decryptdata = key.getDecryptData(this.sn);
+        this._decryptdata = key.getDecryptData(this.sn, this.levelkeys);
       }
     }
   }

src/loader/level-key.ts

@@ -100,7 +100,10 @@ export class LevelKey implements DecryptData {
     return false;
   }
 
-  public getDecryptData(sn: number | 'initSegment'): LevelKey | null {
+  public getDecryptData(
+    sn: number | 'initSegment',
+    levelKeys?: { [key: string]: LevelKey | undefined },
+  ): LevelKey | null {
     if (!this.encrypted || !this.uri) {
       return null;
     }
@@ -135,10 +138,19 @@ export class LevelKey implements DecryptData {
       return this;
     }
 
-    if (this.pssh && this.keyId) {
-      return this;
+    if (this.keyId) {
+      // Handle case where key id is changed in KEY_LOADING event handler #7542#issuecomment-3305203929
+      const assignedKeyId = keyUriToKeyIdMap[this.uri];
+      if (assignedKeyId && !arrayValuesMatch(this.keyId, assignedKeyId)) {
+        LevelKey.setKeyIdForUri(this.uri, this.keyId);
+      }
+
+      if (this.pssh) {
+        return this;
+      }
     }
 
+    // Key bytes are signalled the KEYID attribute, typically only found on WideVine KEY tags
     // Initialize keyId if possible
     const keyBytes = convertDataUriToArrayBytes(this.uri);
     if (keyBytes) {
@@ -156,8 +168,11 @@ export class LevelKey implements DecryptData {
             }
           }
           if (!this.keyId) {
-            const offset = keyBytes.length - 22;
-            this.keyId = keyBytes.subarray(offset, offset + 16);
+            this.keyId = getKeyIdFromPlayReadyKey(levelKeys);
+            if (!this.keyId) {
+              const offset = keyBytes.length - 22;
+              this.keyId = keyBytes.subarray(offset, offset + 16);
+            }
           }
           break;
         case KeySystemFormats.PLAYREADY: {
@@ -189,13 +204,20 @@ export class LevelKey implements DecryptData {
 
     // Default behavior: assign a new keyId for each uri
     if (!this.keyId || this.keyId.byteLength !== 16) {
-      let keyId = keyUriToKeyIdMap[this.uri];
+      let keyId: Uint8Array<ArrayBuffer> | null | undefined =
+        keyUriToKeyIdMap[this.uri];
       if (!keyId) {
-        const val =
-          Object.keys(keyUriToKeyIdMap).length % Number.MAX_SAFE_INTEGER;
-        keyId = new Uint8Array(16);
-        const dv = new DataView(keyId.buffer, 12, 4); // Just set the last 4 bytes
-        dv.setUint32(0, val);
+        keyId = getKeyIdFromWidevineKey(levelKeys);
+        if (!keyId) {
+          keyId = getKeyIdFromPlayReadyKey(levelKeys);
+          if (!keyId) {
+            const val =
+              Object.keys(keyUriToKeyIdMap).length % Number.MAX_SAFE_INTEGER;
+            keyId = new Uint8Array(16);
+            const dv = new DataView(keyId.buffer, 12, 4); // Just set the last 4 bytes
+            dv.setUint32(0, val);
+          }
+        }
         LevelKey.setKeyIdForUri(this.uri, keyId);
       }
       this.keyId = keyId;
@@ -205,6 +227,29 @@ export class LevelKey implements DecryptData {
   }
 }
 
+function getKeyIdFromWidevineKey(
+  levelKeys: { [key: string]: LevelKey | undefined } | undefined,
+) {
+  const widevineKey = levelKeys?.[KeySystemFormats.WIDEVINE];
+  if (widevineKey) {
+    return widevineKey.keyId;
+  }
+  return null;
+}
+
+function getKeyIdFromPlayReadyKey(
+  levelKeys: { [key: string]: LevelKey | undefined } | undefined,
+) {
+  const playReadyKey = levelKeys?.[KeySystemFormats.PLAYREADY];
+  if (playReadyKey) {
+    const playReadyKeyBytes = convertDataUriToArrayBytes(playReadyKey.uri);
+    if (playReadyKeyBytes) {
+      return parsePlayReadyWRM(playReadyKeyBytes);
+    }
+  }
+  return null;
+}
+
 function createInitializationVector(segmentNumber: number) {
   const uint8View = new Uint8Array(16);
   for (let i = 12; i < 16; i++) {