feat(qmcv2): Experiment with qmc2-crypto

(cherry picked from commit c8eb1bc481347efb6d35e9122e17e624bde18772)

package-lock.json

@@ -10,6 +10,7 @@
       "license": "MIT",
       "dependencies": {
         "@babel/preset-typescript": "^7.16.5",
+        "@jixun/qmc2-crypto": "^0.0.5-R2",
         "base64-js": "^1.5.1",
         "browser-id3-writer": "^4.4.0",
         "core-js": "^3.16.0",
@@ -2980,6 +2981,11 @@
         "regenerator-runtime": "^0.13.3"
       }
     },
+    "node_modules/@jixun/qmc2-crypto": {
+      "version": "0.0.5-R2",
+      "resolved": "https://registry.npmjs.org/@jixun/qmc2-crypto/-/qmc2-crypto-0.0.5-R2.tgz",
+      "integrity": "sha512-omrsnXSx7BpOCY8Yla+xwil0bYz/4sj3qEFy4hu4JL/ujeWMzASKq9WnW+UHfSnLUw6EGstub+CoSXrFeRDfqQ=="
+    },
     "node_modules/@mrmlnc/readdir-enhanced": {
       "version": "2.2.1",
       "resolved": "https://registry.npmjs.org/@mrmlnc/readdir-enhanced/-/readdir-enhanced-2.2.1.tgz",
@@ -23019,6 +23025,11 @@
         "regenerator-runtime": "^0.13.3"
       }
     },
+    "@jixun/qmc2-crypto": {
+      "version": "0.0.5-R2",
+      "resolved": "https://registry.npmjs.org/@jixun/qmc2-crypto/-/qmc2-crypto-0.0.5-R2.tgz",
+      "integrity": "sha512-omrsnXSx7BpOCY8Yla+xwil0bYz/4sj3qEFy4hu4JL/ujeWMzASKq9WnW+UHfSnLUw6EGstub+CoSXrFeRDfqQ=="
+    },
     "@mrmlnc/readdir-enhanced": {
       "version": "2.2.1",
       "resolved": "https://registry.npmjs.org/@mrmlnc/readdir-enhanced/-/readdir-enhanced-2.2.1.tgz",

package.json

@@ -18,6 +18,7 @@
   },
   "dependencies": {
     "@babel/preset-typescript": "^7.16.5",
+    "@jixun/qmc2-crypto": "^0.0.5-R2",
     "base64-js": "^1.5.1",
     "browser-id3-writer": "^4.4.0",
     "core-js": "^3.16.0",

src/decrypt/qmc.ts

@@ -9,6 +9,7 @@ import {
     SniffAudioExt, WriteMetaToFlac, WriteMetaToMp3
 } from "@/decrypt/utils";
 import {parseBlob as metaParseBlob} from "music-metadata-browser";
+import {decryptMGG} from "./qmcv2";
 
 
 import iconv from "iconv-lite";
@@ -42,31 +43,35 @@ export const HandlerMap: { [key: string]: Handler } = {
     "776176": {handler: QmcMaskGetDefault, ext: "wav", detect: false}
 };
 
+function mergeUint8(array: Uint8Array[]): Uint8Array {
+    // Get the total length of all arrays.
+    let length = 0;
+    array.forEach(item => {
+      length += item.length;
+    });
+
+    // Create a new array with total length and merge all source arrays.
+    let mergedArray = new Uint8Array(length);
+    let offset = 0;
+    array.forEach(item => {
+      mergedArray.set(item, offset);
+      offset += item.length;
+    });
+
+    return mergedArray;
+}
+
 export async function Decrypt(file: Blob, raw_filename: string, raw_ext: string): Promise<DecryptResult> {
     if (!(raw_ext in HandlerMap)) throw `Qmc cannot handle type: ${raw_ext}`;
     const handler = HandlerMap[raw_ext];
 
-    const fileData = new Uint8Array(await GetArrayBuffer(file));
-    let audioData, seed, keyData;
-    if (handler.detect) {
-        const keyLen = new DataView(fileData.slice(fileData.length - 4).buffer).getUint32(0, true)
-        const keyPos = fileData.length - 4 - keyLen;
-        audioData = fileData.slice(0, keyPos);
-        seed = handler.handler(audioData);
-        keyData = fileData.slice(keyPos, keyPos + keyLen);
-        if (!seed) seed = await queryKey(keyData, raw_filename, raw_ext);
-        if (!seed) throw raw_ext + "格式仅提供实验性支持";
-    } else {
-        audioData = fileData;
-        seed = handler.handler(audioData) as QmcMask;
-        if (!seed) throw raw_ext + "格式仅提供实验性支持";
-    }
-    let musicDecoded = seed.Decrypt(audioData);
+    const decodedParts = await decryptMGG(await file.arrayBuffer());
+    let musicDecoded = mergeUint8(decodedParts);
 
     const ext = SniffAudioExt(musicDecoded, handler.ext);
     const mime = AudioMimeType[ext];
 
-    let musicBlob = new Blob([musicDecoded], {type: mime});
+    let musicBlob = new Blob(decodedParts, {type: mime});
 
     const musicMeta = await metaParseBlob(musicBlob);
     for (let metaIdx in musicMeta.native) {
@@ -80,8 +85,6 @@ export async function Decrypt(file: Blob, raw_filename: string, raw_ext: string)
     }
 
     const info = GetMetaFromFile(raw_filename, musicMeta.common.title, musicMeta.common.artist)
-    if (keyData) reportKeyUsage(keyData, seed.getMatrix128(),
-        raw_filename, raw_ext, info.title, info.artist, musicMeta.common.album).then().catch();
 
     let imgUrl = GetCoverFromFile(musicMeta);
     if (!imgUrl) {

src/decrypt/qmcv2.ts

@@ -0,0 +1,95 @@
+import QMCCryptoModule from '@jixun/qmc2-crypto';
+
+// EOF Magic detection.
+const DETECTION_SIZE = 40;
+
+// Process in 2m buffer size
+const DECRYPTION_BUF_SIZE = 2 * 1024 * 1024;
+
+/**
+ * 解密一个 QMC2 加密的文件。
+ *
+ * 如果检测并解密成功，返回解密后的 Uint8Array 数组，按顺序拼接即可得到完整文件。
+ * 若失败，返回 `null`。
+ * @param  {ArrayBuffer} mggBlob 读入的文件 Blob
+ * @param  {string}         name 文件名
+ * @return {Promise<Uint8Array[]|null>}
+ */
+export async function decryptMGG(mggBlob: ArrayBuffer) {
+  // 初始化模组
+  const QMCCrypto = await QMCCryptoModule();
+
+  // 申请内存块，并文件末端数据到 WASM 的内存堆
+  const detectionBuf = new Uint8Array(mggBlob.slice(-DETECTION_SIZE));
+  const pDetectionBuf = QMCCrypto._malloc(detectionBuf.length);
+  QMCCrypto.writeArrayToMemory(detectionBuf, pDetectionBuf);
+
+  // 检测结果内存块
+  const pDetectionResult = QMCCrypto._malloc(QMCCrypto.sizeof_qmc_detection());
+
+  // 进行检测
+  const detectOK = QMCCrypto.detectKeyEndPosition(
+    pDetectionResult,
+    pDetectionBuf,
+    detectionBuf.length
+  );
+
+  // 提取结构体内容：
+  // (pos: i32; len: i32; error: char[??])
+  const position = QMCCrypto.getValue(pDetectionResult, "i32");
+  const len = QMCCrypto.getValue(pDetectionResult + 4, "i32");
+  const detectionError = QMCCrypto.UTF8ToString(pDetectionResult + 8);
+
+  // 释放内存
+  QMCCrypto._free(pDetectionBuf);
+  QMCCrypto._free(pDetectionResult);
+
+  if (detectOK) {
+    // 计算解密后文件的大小。
+    // 之前得到的 position 为相对当前检测数据起点的偏移。
+    const decryptedSize = mggBlob.byteLength - DETECTION_SIZE + position;
+    // $prog.max = decryptedSize;
+
+    // 提取嵌入到文件的 EKey
+    const ekey = new Uint8Array(
+      mggBlob.slice(decryptedSize, decryptedSize + len)
+    );
+
+    // 解码 UTF-8 数据到 string
+    const decoder = new TextDecoder();
+    const ekey_b64 = decoder.decode(ekey);
+
+    // 初始化加密与缓冲区
+    const hCrypto = QMCCrypto.createInstWidthEKey(ekey_b64);
+    const buf = QMCCrypto._malloc(DECRYPTION_BUF_SIZE);
+
+    const decryptedParts = [];
+    let offset = 0;
+    let bytesToDecrypt = decryptedSize;
+    while (bytesToDecrypt > 0) {
+      const blockSize = Math.min(bytesToDecrypt, DECRYPTION_BUF_SIZE);
+
+      // 解密一些片段
+      const blockData = new Uint8Array(
+        mggBlob.slice(offset, offset + blockSize)
+      );
+      QMCCrypto.writeArrayToMemory(blockData, buf);
+      QMCCrypto.decryptStream(hCrypto, buf, offset, blockSize);
+      decryptedParts.push(QMCCrypto.HEAPU8.slice(buf, buf + blockSize));
+
+      offset += blockSize;
+      bytesToDecrypt -= blockSize;
+      // $prog.value = offset;
+
+      // 避免网页卡死，让 event loop 处理一下其它事件。
+      // Worker 应该不需要等待也可以？
+      // await new Promise((resolve) => setTimeout(resolve));
+    }
+    QMCCrypto._free(buf);
+    hCrypto.delete();
+
+    return decryptedParts;
+  } else {
+    throw new Error("ERROR: could not decrypt\n       " + detectionError);
+  }
+}