feat: implement decrypt from user key

src/decrypt-worker/crypto/CryptoFactory.ts

@@ -1,7 +1,7 @@
 import { CryptoFactory } from './CryptoBase';
 
 import { QMC1Crypto } from './qmc/qmc_v1';
-import { QMC2Crypto } from './qmc/qmc_v2';
+import { QMC2Crypto, QMC2CryptoWithKey } from './qmc/qmc_v2';
 import { XiamiCrypto } from './xiami/xiami';
 import { KGMCrypto } from './kgm/kgm_pc';
 import { NCMCrypto } from './ncm/ncm_pc';
@@ -14,6 +14,7 @@ export const allCryptoFactories: CryptoFactory[] = [
   XiamiCrypto.make,
 
   // QMCv2 (*.mflac)
+  QMC2CryptoWithKey.make,
   QMC2Crypto.make,
 
   // NCM (*.ncm)

src/decrypt-worker/crypto/qmc/qmc_v2.ts

@@ -1,16 +1,49 @@
 import { transformBlob } from '~/decrypt-worker/util/transformBlob';
 import type { CryptoBase } from '../CryptoBase';
+import type { DecryptCommandOptions } from '~/decrypt-worker/types.ts';
 import { SEED, ENC_V2_KEY_1, ENC_V2_KEY_2 } from './qmc_v2.key.ts';
+import { fetchParakeet } from '@jixun/libparakeet';
 
 export class QMC2Crypto implements CryptoBase {
   cryptoName = 'QMC/v2';
   checkByDecryptHeader = false;
 
   async decrypt(buffer: ArrayBuffer): Promise<Blob> {
-    return transformBlob(buffer, (p) => p.make.QMCv2(p.make.QMCv2FooterParser(SEED, ENC_V2_KEY_1, ENC_V2_KEY_2)));
+    // FIXME: Move the cleanup to transformBlob
+    const mod = await fetchParakeet();
+    const footerParser = mod.make.QMCv2FooterParser(SEED, ENC_V2_KEY_1, ENC_V2_KEY_2);
+    return transformBlob(buffer, (p) => p.make.QMCv2(footerParser)).finally(() => {
+      footerParser.delete();
+    });
   }
 
   public static make() {
     return new QMC2Crypto();
   }
 }
+
+export class QMC2CryptoWithKey implements CryptoBase {
+  cryptoName = 'QMC/v2 (key)';
+  checkByDecryptHeader = true;
+
+  async checkBySignature(_buffer: ArrayBuffer, options: DecryptCommandOptions): Promise<boolean> {
+    return Boolean(options.qmc2Key);
+  }
+
+  async decrypt(buffer: ArrayBuffer, options: DecryptCommandOptions): Promise<Blob> {
+    if (!options.qmc2Key) {
+      throw new Error('key was not provided');
+    }
+
+    // FIXME: Move the cleanup to transformBlob
+    const mod = await fetchParakeet();
+    const textEncoder = new TextEncoder();
+    const key = textEncoder.encode(options.qmc2Key);
+    const keyCrypto = mod.make.QMCv2KeyCrypto(SEED, ENC_V2_KEY_1, ENC_V2_KEY_2);
+    return transformBlob(buffer, (p) => p.make.QMCv2EKey(key, keyCrypto));
+  }
+
+  public static make() {
+    return new QMC2CryptoWithKey();
+  }
+}