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chore(QMCv2): fix code style 

(cherry picked from commit 87138718549bdec014752ba43dcd5997aaf29137)
20230320
MengYX 3 years ago
parent
fce4734ed9
commit
c1320c811b
No known key found for this signature in database GPG Key ID: E63F9C7303E8F604
5 changed files with 88 additions and 84 deletions
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  1. 17
      src/decrypt/qmc.ts
  2. 46
      src/decrypt/qmc_cipher.ts
  3. 4
      src/decrypt/qmc_key.test.ts
  4. 45
      src/decrypt/qmc_key.ts
  5. 2
      src/decrypt/utils.ts

17
src/decrypt/qmc.ts
View File

@ -1,4 +1,4 @@
import {QmcMapCipher, QmcRC4Cipher, QmcStaticCipher, StreamCipher} from "./qmc_cipher";
import {QmcMapCipher, QmcRC4Cipher, QmcStaticCipher, QmcStreamCipher} from "./qmc_cipher";
import {
AudioMimeType,
GetArrayBuffer,
@ -16,7 +16,7 @@ import {DecryptQMCWasm} from "./qmc_wasm";
import iconv from "iconv-lite";
import {DecryptResult} from "@/decrypt/entity";
import {queryAlbumCover} from "@/utils/api";
import {QmcDecryptKey} from "@/decrypt/qmc_key";
import {QmcDeriveKey} from "@/decrypt/qmc_key";
interface Handler {
ext: string
@ -141,7 +141,8 @@ export class QmcDecoder {
size: number
decoded: boolean = false
audioSize?: number
cipher?: StreamCipher
private static readonly BYTE_COMMA = ','.charCodeAt(0)
cipher?: QmcStreamCipher
constructor(file: Uint8Array) {
this.file = file
@ -167,16 +168,16 @@ export class QmcDecoder {
}
private searchKey() {
const last4Byte = this.file.slice(this.size - 4);
const last4Byte = this.file.slice(-4);
const textEnc = new TextDecoder()
if (textEnc.decode(last4Byte) === 'QTag') {
const sizeBuf = this.file.slice(this.size - 8, this.size - 4)
const sizeBuf = this.file.slice(-8, -4)
const sizeView = new DataView(sizeBuf.buffer, sizeBuf.byteOffset)
const keySize = sizeView.getUint32(0, false)
this.audioSize = this.size - keySize - 8
const rawKey = this.file.subarray(this.audioSize, this.size - 8)
const keyEnd = rawKey.findIndex(v => v == ','.charCodeAt(0))
const keyDec = QmcDecryptKey(rawKey.subarray(0, keyEnd))
const keyEnd = rawKey.findIndex(v => v == QmcDecoder.BYTE_COMMA)
const keyDec = QmcDeriveKey(rawKey.subarray(0, keyEnd))
this.cipher = new QmcRC4Cipher(keyDec)
} else {
const sizeView = new DataView(last4Byte.buffer, last4Byte.byteOffset);
@ -184,7 +185,7 @@ export class QmcDecoder {
if (keySize < 0x300) {
this.audioSize = this.size - keySize - 4
const rawKey = this.file.subarray(this.audioSize, this.size - 4)
const keyDec = QmcDecryptKey(rawKey)
const keyDec = QmcDeriveKey(rawKey)
this.cipher = new QmcMapCipher(keyDec)
} else {
this.audioSize = this.size

46
src/decrypt/qmc_cipher.ts
View File

@ -1,4 +1,10 @@
const staticCipherBox = new Uint8Array([
export interface QmcStreamCipher {
decrypt(buf: Uint8Array, offset: number): void
}
export class QmcStaticCipher implements QmcStreamCipher {
private static readonly staticCipherBox: Uint8Array = 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
@ -31,17 +37,11 @@ const staticCipherBox = new Uint8Array([
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
])
export 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]
return QmcStaticCipher.staticCipherBox[(offset * offset + 27) & 0xff]
}
public decrypt(buf: Uint8Array, offset: number) {
@ -51,7 +51,7 @@ export class QmcStaticCipher implements StreamCipher {
}
}
export class QmcMapCipher implements StreamCipher {
export class QmcMapCipher implements QmcStreamCipher {
key: Uint8Array
n: number
@ -84,10 +84,10 @@ export class QmcMapCipher implements StreamCipher {
}
const FIRST_SEGMENT_SIZE = 0x80;
const SEGMENT_SIZE = 5120
export class QmcRC4Cipher implements QmcStreamCipher {
private static readonly FIRST_SEGMENT_SIZE = 0x80;
private static readonly SEGMENT_SIZE = 5120
export class QmcRC4Cipher implements StreamCipher {
S: Uint8Array
N: number
key: Uint8Array
@ -139,23 +139,23 @@ export class QmcRC4Cipher implements StreamCipher {
}
// Initial segment
if (offset < FIRST_SEGMENT_SIZE) {
const len_segment = Math.min(buf.length, FIRST_SEGMENT_SIZE - offset);
if (offset < QmcRC4Cipher.FIRST_SEGMENT_SIZE) {
const len_segment = Math.min(buf.length, QmcRC4Cipher.FIRST_SEGMENT_SIZE - offset);
this.encFirstSegment(buf.subarray(0, len_segment), offset);
if (postProcess(len_segment)) return
}
// align segment
if (offset % SEGMENT_SIZE != 0) {
const len_segment = Math.min(SEGMENT_SIZE - (offset % SEGMENT_SIZE), toProcess);
if (offset % QmcRC4Cipher.SEGMENT_SIZE != 0) {
const len_segment = Math.min(QmcRC4Cipher.SEGMENT_SIZE - (offset % QmcRC4Cipher.SEGMENT_SIZE), toProcess);
this.encASegment(buf.subarray(processed, processed + len_segment), offset);
if (postProcess(len_segment)) return
}
// Batch process segments
while (toProcess > SEGMENT_SIZE) {
this.encASegment(buf.subarray(processed, processed + SEGMENT_SIZE), offset);
postProcess(SEGMENT_SIZE)
while (toProcess > QmcRC4Cipher.SEGMENT_SIZE) {
this.encASegment(buf.subarray(processed, processed + QmcRC4Cipher.SEGMENT_SIZE), offset);
postProcess(QmcRC4Cipher.SEGMENT_SIZE)
}
// Last segment (incomplete segment)
@ -168,7 +168,7 @@ export class QmcRC4Cipher implements StreamCipher {
private encFirstSegment(buf: Uint8Array, offset: number) {
for (let i = 0; i < buf.length; i++) {
buf[i] ^= this.key[this.getSegmentSkip(offset + i)];
buf[i] ^= this.key[this.getSegmentKey(offset + i)];
}
}
@ -178,7 +178,7 @@ export class QmcRC4Cipher implements StreamCipher {
// Calculate the number of bytes to skip.
// The initial "key" derived from segment id, plus the current offset.
const skipLen = (offset % SEGMENT_SIZE) + this.getSegmentSkip(offset / SEGMENT_SIZE)
const skipLen = (offset % QmcRC4Cipher.SEGMENT_SIZE) + this.getSegmentKey(offset / QmcRC4Cipher.SEGMENT_SIZE)
// decrypt the block
let j = 0;
@ -194,7 +194,7 @@ export class QmcRC4Cipher implements StreamCipher {
}
}
private getSegmentSkip(id: number): number {
private getSegmentKey(id: number): number {
const seed = this.key[id % this.N]
const idx = (this.hash / ((id + 1) * seed) * 100.0) | 0;
return idx % this.N

4
src/decrypt/qmc_key.test.ts
View File

@ -1,4 +1,4 @@
import {QmcDecryptKey, simpleMakeKey,} from "@/decrypt/qmc_key";
import {QmcDeriveKey, simpleMakeKey} from "@/decrypt/qmc_key";
import fs from "fs";
test("key dec: make simple key", () => {
@ -23,7 +23,7 @@ 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 = QmcDecryptKey(cipherText)
const buf = QmcDeriveKey(cipherText)
expect(buf).toStrictEqual(clearText)
}

45
src/decrypt/qmc_key.ts
View File

@ -1,5 +1,29 @@
import {TeaCipher} from "@/utils/tea";
const SALT_LEN = 2
const ZERO_LEN = 7
export function QmcDeriveKey(raw: Uint8Array): Uint8Array {
const textDec = new TextDecoder()
const rawDec = Buffer.from(textDec.decode(raw), '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)
}
// simpleMakeKey exported only for unit test
export function simpleMakeKey(salt: number, length: number): number[] {
const keyBuf: number[] = []
for (let i = 0; i < length; i++) {
@ -9,8 +33,6 @@ export function simpleMakeKey(salt: number, length: number): number[] {
return keyBuf
}
const SALT_LEN = 2
const ZERO_LEN = 7
function decryptTencentTea(inBuf: Uint8Array, key: Uint8Array): Uint8Array {
if (inBuf.length % 8 != 0) {
@ -83,22 +105,3 @@ function decryptTencentTea(inBuf: Uint8Array, key: Uint8Array): Uint8Array {
return outBuf
}
export function QmcDecryptKey(raw: Uint8Array): Uint8Array {
const textDec = new TextDecoder()
const rawDec = Buffer.from(textDec.decode(raw), '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)
}

2
src/decrypt/utils.ts
View File

@ -33,7 +33,7 @@ export function BytesHasPrefix(data: Uint8Array, prefix: number[]): boolean {
}
export function BytesEqual(a: Uint8Array, b: Uint8Array,): boolean {
if (a.length != b.length) return false
if (a.length !== b.length) return false
return a.every((val, idx) => {
return val === b[idx];
})

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