feat(QMCv2): add key decrypt

(cherry picked from commit a9aaa40ec48a75967882ef95951bf4f7fccf7a9d)

src/decrypt/qmc_key.test.ts

@@ -0,0 +1,30 @@
+import {DecryptKey, simpleMakeKey,} from "@/decrypt/qmc_key";
+import fs from "fs";
+
+test("key dec: make simple key", () => {
+  expect(
+    simpleMakeKey(106, 8)
+  ).toStrictEqual(
+    [0x69, 0x56, 0x46, 0x38, 0x2b, 0x20, 0x15, 0x0b]
+  )
+})
+
+function loadTestDataKeyDecrypt(name: string): {
+  cipherText: Uint8Array,
+  clearText: Uint8Array
+} {
+  return {
+    cipherText: fs.readFileSync(`testdata/${name}_key_raw.bin`),
+    clearText: fs.readFileSync(`testdata/${name}_key.bin`)
+  }
+}
+
+test("key dec: real file", async () => {
+  const cases = ["mflac_map", "mgg_map", "mflac0_rc4"]
+  for (const name of cases) {
+    const {clearText, cipherText} = loadTestDataKeyDecrypt(name)
+    const buf = DecryptKey(cipherText)
+
+    expect(buf).toStrictEqual(clearText)
+  }
+})

src/decrypt/qmc_key.ts

@@ -0,0 +1,103 @@
+import {TeaCipher} from "@/utils/tea";
+
+export function simpleMakeKey(salt: number, length: number): number[] {
+  const keyBuf: number[] = []
+  for (let i = 0; i < length; i++) {
+    const tmp = Math.tan(salt + i * 0.1)
+    keyBuf[i] = 0xff & (Math.abs(tmp) * 100.0)
+  }
+  return keyBuf
+}
+
+const SALT_LEN = 2
+const ZERO_LEN = 7
+
+function decryptTencentTea(inBuf: Uint8Array, key: Uint8Array): Uint8Array {
+  if (inBuf.length % 8 != 0) {
+    throw Error("inBuf size not a multiple of the block size")
+  }
+  if (inBuf.length < 16) {
+    throw Error("inBuf size too small")
+  }
+
+  const blk = new TeaCipher(key, 32)
+
+  const tmpBuf = new Uint8Array(8);
+  const tmpView = new DataView(tmpBuf.buffer);
+
+  blk.decrypt(tmpView, new DataView(inBuf.buffer, inBuf.byteOffset, 8))
+
+  const nPadLen = tmpBuf[0] & 0x7;//只要最低三位
+  /*密文格式:PadLen(1byte)+Padding(var,0-7byte)+Salt(2byte)+Body(var byte)+Zero(7byte)*/
+  const outLen = inBuf.length - 1 /*PadLen*/ - nPadLen - SALT_LEN - ZERO_LEN;
+  const outBuf = new Uint8Array(outLen)
+
+  let ivPrev = new Uint8Array(8);
+  let ivCur = inBuf.slice(0, 8); // init iv
+  let inBufPos = 8;
+
+
+  // 跳过 Padding Len 和 Padding
+  let tmpIdx = 1 + nPadLen;
+
+  // CBC IV 处理
+  const cryptBlock = () => {
+    ivPrev = ivCur;
+    ivCur = inBuf.slice(inBufPos, inBufPos + 8)
+    for (let j = 0; j < 8; j++) {
+      tmpBuf[j] ^= ivCur[j]
+    }
+    blk.decrypt(tmpView, tmpView)
+    inBufPos += 8;
+    tmpIdx = 0;
+  }
+
+  // 跳过 Salt
+  for (let i = 1; i <= SALT_LEN;) {
+    if (tmpIdx < 8) {
+      tmpIdx++;
+      i++;
+    } else {
+      cryptBlock()
+    }
+  }
+
+  // 还原明文
+  let outBufPos = 0;
+  while (outBufPos < outLen) {
+    if (tmpIdx < 8) {
+      outBuf[outBufPos] = tmpBuf[tmpIdx] ^ ivPrev[tmpIdx];
+      outBufPos++
+      tmpIdx++;
+    } else {
+      cryptBlock()
+    }
+  }
+
+  // 校验Zero
+  for (let i = 1; i <= ZERO_LEN; i++) {
+    if (tmpBuf[tmpIdx] != ivPrev[tmpIdx]) {
+      throw Error("zero check failed")
+    }
+  }
+  return outBuf
+}
+
+export function DecryptKey(raw: Uint8Array): Uint8Array {
+  const rawDec = Buffer.from(raw.toString(), 'base64')
+  let n = rawDec.length;
+  if (n < 16) {
+    throw Error("key length is too short")
+  }
+
+  const simpleKey = simpleMakeKey(106, 8)
+  let teaKey = new Uint8Array(16);
+  for (let i = 0; i < 8; i++) {
+    teaKey[i << 1] = simpleKey[i];
+    teaKey[(i << 1) + 1] = rawDec[i];
+  }
+  const sub = decryptTencentTea(rawDec.subarray(8), teaKey)
+  rawDec.set(sub, 8)
+  return rawDec.subarray(0, 8 + sub.length)
+
+}

testdata/mflac0_rc4_key.bin

@@ -0,0 +1 @@
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testdata/mflac0_rc4_key_raw.bin

@@ -0,0 +1 @@
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testdata/mflac_map_key.bin

@@ -0,0 +1 @@
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testdata/mflac_map_key_raw.bin

@@ -0,0 +1 @@
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testdata/mgg_map_key.bin

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testdata/mgg_map_key_raw.bin

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