feat: use static cipher instead of mask

(cherry picked from commit cd6b84ad7eed489f9bcbd72d847cd4d704052b0c)

src/decrypt/qmc.ts

@@ -1,12 +1,13 @@
-import {QmcMask, QmcMaskGetDefault} from "./qmcMask";
+import {QmcStaticCipher} from "./qmc_cipher";
-import {toByteArray as Base64Decode} from 'base64-js'
 import {
   AudioMimeType,
   GetArrayBuffer,
   GetCoverFromFile,
   GetImageFromURL,
   GetMetaFromFile,
-    SniffAudioExt, WriteMetaToFlac, WriteMetaToMp3
+  SniffAudioExt,
+  WriteMetaToFlac,
+  WriteMetaToMp3
 } from "@/decrypt/utils";
 import {parseBlob as metaParseBlob} from "music-metadata-browser";
 import {DecryptQMCv2} from "./qmcv2";
@@ -14,7 +15,7 @@ import {DecryptQMCv2} from "./qmcv2";
 
 import iconv from "iconv-lite";
 import {DecryptResult} from "@/decrypt/entity";
-import {queryAlbumCover, queryKeyInfo, reportKeyUsage} from "@/utils/api";
+import {queryAlbumCover} from "@/utils/api";
 
 interface Handler {
   ext: string
@@ -48,10 +49,10 @@ export const HandlerMap: { [key: string]: Handler } = {
 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];
-    let { version } = handler;
+  let {version} = handler;
 
   const fileBuffer = await GetArrayBuffer(file);
-    let musicDecoded: Uint8Array|undefined;
+  let musicDecoded: Uint8Array | undefined;
 
   if (version === 2) {
     const v2Decrypted = await DecryptQMCv2(fileBuffer);
@@ -64,8 +65,9 @@ export async function Decrypt(file: Blob, raw_filename: string, raw_ext: string)
   }
 
   if (version === 1) {
-        const seed = QmcMaskGetDefault();
+    const seed = new QmcStaticCipher();
-        musicDecoded = seed.Decrypt(new Uint8Array(fileBuffer));
+    musicDecoded = new Uint8Array(fileBuffer)
+    seed.decrypt(musicDecoded, 0);
   } else if (!musicDecoded) {
     throw new Error(`解密失败: ${raw_ext}`);
   }
@@ -125,15 +127,6 @@ export async function Decrypt(file: Blob, raw_filename: string, raw_ext: string)
 }
 
 
-async function queryKey(keyData: Uint8Array, filename: string, format: string): Promise<QmcMask | undefined> {
-    try {
-        const data = await queryKeyInfo(keyData, filename, format)
-        return new QmcMask(Base64Decode(data.Matrix44));
-    } catch (e) {
-        console.warn(e);
-    }
-}
-
 async function getCoverImage(title: string, artist?: string, album?: string): Promise<string> {
   const song_query_url = "https://stats.ixarea.com/apis" + "/music/qq-cover"
   try {

src/decrypt/qmcMask.ts

@@ -1,98 +0,0 @@
-const QMCDefaultMaskMatrix = [
-    0xde, 0x51, 0xfa, 0xc3, 0x4a, 0xd6, 0xca, 0x90,
-    0x7e, 0x67, 0x5e, 0xf7, 0xd5, 0x52, 0x84, 0xd8,
-    0x47, 0x95, 0xbb, 0xa1, 0xaa, 0xc6, 0x66, 0x23,
-    0x92, 0x62, 0xf3, 0x74, 0xa1, 0x9f, 0xf4, 0xa0,
-    0x1d, 0x3f, 0x5b, 0xf0, 0x13, 0x0e, 0x09, 0x3d,
-    0xf9, 0xbc, 0x00, 0x11];
-
-const AllMapping: number[][] = [];
-const Mask128to44: number[] = [];
-
-(function () {
-    for (let i = 0; i < 128; i++) {
-        let realIdx = (i * i + 27) % 256
-        if (realIdx in AllMapping) {
-            AllMapping[realIdx].push(i)
-        } else {
-            AllMapping[realIdx] = [i]
-        }
-    }
-
-    let idx44 = 0
-    AllMapping.forEach(all128 => {
-        all128.forEach(_i128 => {
-            Mask128to44[_i128] = idx44
-        })
-        idx44++
-    })
-})();
-
-export class QmcMask {
-    private readonly Matrix128: number[];
-
-    constructor(matrix: number[] | Uint8Array) {
-        if (matrix instanceof Uint8Array) matrix = Array.from(matrix)
-        if (matrix.length === 44) {
-            this.Matrix128 = this._generate128(matrix)
-        } else if (matrix.length === 128) {
-            this.Matrix128 = matrix
-        } else {
-            throw Error("invalid mask length")
-        }
-    }
-
-    getMatrix128() {
-        return this.Matrix128
-    }
-
-    getMatrix44(): number[] {
-        const matrix44: number[] = []
-        let idxI44 = 0
-        AllMapping.forEach(it256 => {
-            let it256Len = it256.length
-            for (let i = 1; i < it256Len; i++) {
-                if (this.Matrix128[it256[0]] !== this.Matrix128[it256[i]]) {
-                    throw "decode mask-128 to mask-44 failed"
-                }
-            }
-            matrix44[idxI44] = this.Matrix128[it256[0]]
-            idxI44++
-        })
-        return matrix44
-    }
-
-    Decrypt(data: Uint8Array) {
-        if (!this.Matrix128) throw Error("bad call sequence")
-        let dst = data.slice(0);
-        let index = -1;
-        let maskIdx = -1;
-        for (let cur = 0; cur < data.length; cur++) {
-            index++;
-            maskIdx++;
-            if (index === 0x8000 || (index > 0x8000 && (index + 1) % 0x8000 === 0)) {
-                index++;
-                maskIdx++;
-            }
-            if (maskIdx >= 128) maskIdx -= 128;
-            dst[cur] ^= this.Matrix128[maskIdx];
-        }
-        return dst;
-    }
-
-    private _generate128(matrix44: number[]): number[] {
-        const matrix128: number[] = []
-        let idx44 = 0
-        AllMapping.forEach(it256 => {
-            it256.forEach(m => {
-                matrix128[m] = matrix44[idx44]
-            })
-            idx44++
-        })
-        return matrix128
-    }
-}
-
-export function QmcMaskGetDefault() {
-    return new QmcMask(QMCDefaultMaskMatrix)
-}

src/decrypt/qmc_cipher.test.ts

@@ -0,0 +1,27 @@
+import {QmcStaticCipher} from "@/decrypt/qmc_cipher";
+
+test("static cipher [0x7ff8,0x8000) ", () => {
+  const expected = new Uint8Array([
+    0xD8, 0x52, 0xF7, 0x67, 0x90, 0xCA, 0xD6, 0x4A,
+    0x4A, 0xD6, 0xCA, 0x90, 0x67, 0xF7, 0x52, 0xD8,
+  ])
+
+  const c = new QmcStaticCipher()
+  const buf = new Uint8Array(16)
+  c.decrypt(buf, 0x7ff8)
+
+  expect(buf).toStrictEqual(expected)
+})
+
+test("static cipher [0,0x10) ", () => {
+  const expected = new Uint8Array([
+    0xC3, 0x4A, 0xD6, 0xCA, 0x90, 0x67, 0xF7, 0x52,
+    0xD8, 0xA1, 0x66, 0x62, 0x9F, 0x5B, 0x09, 0x00,
+  ])
+
+  const c = new QmcStaticCipher()
+  const buf = new Uint8Array(16)
+  c.decrypt(buf, 0)
+
+  expect(buf).toStrictEqual(expected)
+})

src/decrypt/qmc_cipher.ts

@@ -0,0 +1,53 @@
+const staticCipherBox = new Uint8Array([
+  0x77, 0x48, 0x32, 0x73, 0xDE, 0xF2, 0xC0, 0xC8, //0x00
+  0x95, 0xEC, 0x30, 0xB2, 0x51, 0xC3, 0xE1, 0xA0, //0x08
+  0x9E, 0xE6, 0x9D, 0xCF, 0xFA, 0x7F, 0x14, 0xD1, //0x10
+  0xCE, 0xB8, 0xDC, 0xC3, 0x4A, 0x67, 0x93, 0xD6, //0x18
+  0x28, 0xC2, 0x91, 0x70, 0xCA, 0x8D, 0xA2, 0xA4, //0x20
+  0xF0, 0x08, 0x61, 0x90, 0x7E, 0x6F, 0xA2, 0xE0, //0x28
+  0xEB, 0xAE, 0x3E, 0xB6, 0x67, 0xC7, 0x92, 0xF4, //0x30
+  0x91, 0xB5, 0xF6, 0x6C, 0x5E, 0x84, 0x40, 0xF7, //0x38
+  0xF3, 0x1B, 0x02, 0x7F, 0xD5, 0xAB, 0x41, 0x89, //0x40
+  0x28, 0xF4, 0x25, 0xCC, 0x52, 0x11, 0xAD, 0x43, //0x48
+  0x68, 0xA6, 0x41, 0x8B, 0x84, 0xB5, 0xFF, 0x2C, //0x50
+  0x92, 0x4A, 0x26, 0xD8, 0x47, 0x6A, 0x7C, 0x95, //0x58
+  0x61, 0xCC, 0xE6, 0xCB, 0xBB, 0x3F, 0x47, 0x58, //0x60
+  0x89, 0x75, 0xC3, 0x75, 0xA1, 0xD9, 0xAF, 0xCC, //0x68
+  0x08, 0x73, 0x17, 0xDC, 0xAA, 0x9A, 0xA2, 0x16, //0x70
+  0x41, 0xD8, 0xA2, 0x06, 0xC6, 0x8B, 0xFC, 0x66, //0x78
+  0x34, 0x9F, 0xCF, 0x18, 0x23, 0xA0, 0x0A, 0x74, //0x80
+  0xE7, 0x2B, 0x27, 0x70, 0x92, 0xE9, 0xAF, 0x37, //0x88
+  0xE6, 0x8C, 0xA7, 0xBC, 0x62, 0x65, 0x9C, 0xC2, //0x90
+  0x08, 0xC9, 0x88, 0xB3, 0xF3, 0x43, 0xAC, 0x74, //0x98
+  0x2C, 0x0F, 0xD4, 0xAF, 0xA1, 0xC3, 0x01, 0x64, //0xA0
+  0x95, 0x4E, 0x48, 0x9F, 0xF4, 0x35, 0x78, 0x95, //0xA8
+  0x7A, 0x39, 0xD6, 0x6A, 0xA0, 0x6D, 0x40, 0xE8, //0xB0
+  0x4F, 0xA8, 0xEF, 0x11, 0x1D, 0xF3, 0x1B, 0x3F, //0xB8
+  0x3F, 0x07, 0xDD, 0x6F, 0x5B, 0x19, 0x30, 0x19, //0xC0
+  0xFB, 0xEF, 0x0E, 0x37, 0xF0, 0x0E, 0xCD, 0x16, //0xC8
+  0x49, 0xFE, 0x53, 0x47, 0x13, 0x1A, 0xBD, 0xA4, //0xD0
+  0xF1, 0x40, 0x19, 0x60, 0x0E, 0xED, 0x68, 0x09, //0xD8
+  0x06, 0x5F, 0x4D, 0xCF, 0x3D, 0x1A, 0xFE, 0x20, //0xE0
+  0x77, 0xE4, 0xD9, 0xDA, 0xF9, 0xA4, 0x2B, 0x76, //0xE8
+  0x1C, 0x71, 0xDB, 0x00, 0xBC, 0xFD, 0x0C, 0x6C, //0xF0
+  0xA5, 0x47, 0xF7, 0xF6, 0x00, 0x79, 0x4A, 0x11, //0xF8
+])
+
+interface streamCipher {
+  decrypt(buf: Uint8Array, offset: number): void
+}
+
+export class QmcStaticCipher implements streamCipher {
+
+  public getMask(offset: number) {
+    if (offset > 0x7FFF) offset %= 0x7FFF
+    return staticCipherBox[(offset * offset + 27) & 0xff]
+  }
+
+  public decrypt(buf: Uint8Array, offset: number) {
+    for (let i = 0; i < buf.length; i++) {
+      buf[i] ^= this.getMask(offset + i)
+    }
+  }
+}
+

src/decrypt/qmcv2.ts

@@ -27,7 +27,6 @@ function MergeUint8Array(array: Uint8Array[]): Uint8Array {
  *
  * 如果检测并解密成功，返回解密后的 Uint8Array 数据。
  * @param  {ArrayBuffer} mggBlob 读入的文件 Blob
- * @param  {string}         name 文件名
  * @return {Promise<Uint8Array|false>}
  */
 export async function DecryptQMCv2(mggBlob: ArrayBuffer) {