src/crypto/pasreKuwo.ts

@@ -0,0 +1,25 @@
+import { bytesToUTF8String } from '~/decrypt-worker/util/utf8Encoder';
+import { strlen } from './strlen';
+
+export interface KuwoHeader {
+  rid: string; // uint64
+  encVersion: 1 | 2; // uint32
+  quality: string;
+}
+
+export function parseKuwoHeader(view: DataView): KuwoHeader | null {
+  const magic = view.buffer.slice(view.byteOffset, view.byteOffset + 0x10);
+  if (bytesToUTF8String(magic) !== 'yeelion-kuwo-tme') {
+    return null; // not kuwo-encrypted file
+  }
+
+  const qualityBytes = new Uint8Array(view.buffer.slice(view.byteOffset + 0x30, view.byteOffset + 0x40));
+  const qualityLen = strlen(qualityBytes);
+  const quality = bytesToUTF8String(qualityBytes.slice(0, qualityLen));
+
+  return {
+    encVersion: view.getUint32(0x10, true) as 1 | 2,
+    rid: view.getUint32(0x18, true).toString(),
+    quality,
+  };
+}

src/crypto/strlen.ts

@@ -0,0 +1,9 @@
+export function strlen(data: Uint8Array): number {
+  const n = data.byteLength;
+  for (let i = 0; i < n; i++) {
+    if (data[i] === 0) {
+      return i;
+    }
+  }
+  return n;
+}

src/decrypt-worker/crypto/kwm/kwm.ts

@@ -1,14 +1,25 @@
 import { transformBlob } from '~/decrypt-worker/util/transformBlob';
 import type { CryptoBase } from '../CryptoBase';
 import { KWM_KEY } from './kwm.key';
+import { DecryptCommandOptions } from '~/decrypt-worker/types';
+import { makeQMCv2KeyCrypto } from '~/decrypt-worker/util/qmc2KeyCrypto';
+import { fetchParakeet } from '@jixun/libparakeet';
+import { stringToUTF8Bytes } from '~/decrypt-worker/util/utf8Encoder';
 
 // v1 only
 export class KWMCrypto implements CryptoBase {
   cryptoName = 'KWM';
   checkByDecryptHeader = true;
 
-  async decrypt(buffer: ArrayBuffer): Promise<Blob> {
-    return transformBlob(buffer, (p) => p.make.KuwoKWM(KWM_KEY));
+  async decrypt(buffer: ArrayBuffer, opts: DecryptCommandOptions): Promise<Blob> {
+    const kwm2key = opts.kwm2key ?? '';
+
+    const parakeet = await fetchParakeet();
+    const keyCrypto = makeQMCv2KeyCrypto(parakeet);
+    return transformBlob(buffer, (p) => p.make.KuwoKWMv2(KWM_KEY, stringToUTF8Bytes(kwm2key), keyCrypto), {
+      cleanup: () => keyCrypto.delete(),
+      parakeet,
+    });
   }
 
   public static make() {

src/decrypt-worker/types.ts

@@ -1,5 +1,6 @@
 export interface DecryptCommandOptions {
   qmc2Key?: string;
+  kwm2key?: string;
 }
 
 export interface DecryptCommandPayload {

src/features/file-listing/fileListingSlice.ts

@@ -1,11 +1,12 @@
 import { createSlice, createAsyncThunk } from '@reduxjs/toolkit';
 import type { PayloadAction } from '@reduxjs/toolkit';
 import type { RootState } from '~/store';
-import { decryptionQueue } from '~/decrypt-worker/client';
 
 import type { DecryptionResult } from '~/decrypt-worker/constants';
+import type { DecryptCommandOptions } from '~/decrypt-worker/types';
+import { decryptionQueue } from '~/decrypt-worker/client';
 import { DecryptErrorType } from '~/decrypt-worker/util/DecryptError';
-import { selectDecryptOptionByFile } from '../settings/settingsSelector';
+import { selectQMCv2KeyByFileName, selectKWMv2Key } from '../settings/settingsSelector';
 
 export enum ProcessState {
   QUEUED = 'QUEUED',
@@ -63,7 +64,18 @@ export const processFile = createAsyncThunk<
     thunkAPI.dispatch(setFileAsProcessing({ id: fileId }));
   };
 
-  const options = selectDecryptOptionByFile(state, file.fileName);
+  const fileHeader = await fetch(file.raw, {
+    headers: {
+      Range: 'bytes=0-1023',
+    },
+  })
+    .then((r) => r.blob())
+    .then((r) => r.arrayBuffer());
+
+  const options: DecryptCommandOptions = {
+    qmc2Key: selectQMCv2KeyByFileName(state, file.fileName),
+    kwm2key: selectKWMv2Key(state, new DataView(fileHeader)),
+  };
   return decryptionQueue.add({ id: fileId, blobURI: file.raw, options }, onPreProcess);
 });
 

src/features/settings/keyFormats.ts

@@ -51,6 +51,13 @@ export interface StagingKWMv2Key {
 
 export type ProductionKWMv2Keys = Record<string /* `${rid}-${quality}` */, string /* ekey */>;
 
+export const parseKwm2ProductionKey = (key: string): null | { rid: string; quality: string } => {
+  const m = key.match(/^(\d+)-(\w+)$/);
+  if (!m) return null;
+  const [_, rid, quality] = m;
+
+  return { rid, quality };
+};
 export const kwm2StagingToProductionKey = (key: StagingKWMv2Key) => `${key.rid}-${key.quality}`;
 export const kwm2StagingToProductionValue = (key: StagingKWMv2Key) => key.ekey;
 export const kwm2ProductionToStaging = (
@@ -59,9 +66,8 @@ export const kwm2ProductionToStaging = (
 ): null | StagingKWMv2Key => {
   if (typeof value !== 'string') return null;
 
-  const m = key.match(/^(\d+)-(\w+)$/);
-  if (!m) return null;
+  const parsed = parseKwm2ProductionKey(key);
+  if (!parsed) return null;
 
-  const [_, rid, quality] = m;
-  return { id: nanoid(), rid, quality, ekey: value };
+  return { id: nanoid(), rid: parsed.rid, quality: parsed.quality, ekey: value };
 };

src/features/settings/persistSettings.ts

@@ -5,6 +5,7 @@ import type { AppStore } from '~/store';
 import { settingsSlice, setProductionChanges, ProductionSettings } from './settingsSlice';
 import { enumObject } from '~/util/objects';
 import { getLogger } from '~/util/logUtils';
+import { parseKwm2ProductionKey } from './keyFormats';
 
 const DEFAULT_STORAGE_KEY = 'um-react-settings';
 
@@ -22,6 +23,16 @@ function mergeSettings(settings: ProductionSettings): ProductionSettings {
         draft.qmc2.allowFuzzyNameSearch = allowFuzzyNameSearch;
       }
     }
+
+    if (settings?.kwm2) {
+      const { keys } = settings.kwm2;
+
+      for (const [k, v] of enumObject(keys)) {
+        if (typeof v === 'string' && parseKwm2ProductionKey(k)) {
+          draft.kwm2.keys[k] = v;
+        }
+      }
+    }
   });
 }
 

src/features/settings/settingsSelector.ts

@@ -1,30 +1,47 @@
-import type { DecryptCommandOptions } from '~/decrypt-worker/types';
+import { parseKuwoHeader } from '~/crypto/pasreKuwo';
 import type { RootState } from '~/store';
 import { closestByLevenshtein } from '~/util/levenshtein';
 import { hasOwn } from '~/util/objects';
+import { kwm2StagingToProductionKey } from './keyFormats';
 
 export const selectStagingQMCv2Settings = (state: RootState) => state.settings.staging.qmc2;
 export const selectFinalQMCv2Settings = (state: RootState) => state.settings.production.qmc2;
 
 export const selectStagingKWMv2Keys = (state: RootState) => state.settings.staging.kwm2.keys;
+export const selectFinalKWMv2Keys = (state: RootState) => state.settings.production.kwm2.keys;
 
-export const selectDecryptOptionByFile = (state: RootState, name: string): DecryptCommandOptions => {
+export const selectQMCv2KeyByFileName = (state: RootState, name: string): string | undefined => {
   const normalizedName = name.normalize();
 
-  let qmc2Key: string | undefined;
-  const { keys: qmc2Keys, allowFuzzyNameSearch } = selectFinalQMCv2Settings(state);
-  if (hasOwn(qmc2Keys, normalizedName)) {
-    qmc2Key = qmc2Keys[normalizedName];
+  let ekey: string | undefined;
+  const { keys, allowFuzzyNameSearch } = selectFinalQMCv2Settings(state);
+  if (hasOwn(keys, normalizedName)) {
+    ekey = keys[normalizedName];
   } else if (allowFuzzyNameSearch) {
-    const qmc2KeyStoreNames = Object.keys(qmc2Keys);
+    const qmc2KeyStoreNames = Object.keys(keys);
     if (qmc2KeyStoreNames.length > 0) {
       const closestName = closestByLevenshtein(normalizedName, qmc2KeyStoreNames);
       console.debug('qmc2: key db could not find %o, using closest %o instead.', normalizedName, closestName);
-      qmc2Key = qmc2Keys[closestName];
+      ekey = keys[closestName];
     }
   }
 
-  return {
-    qmc2Key,
-  };
+  return ekey;
+};
+
+export const selectKWMv2Key = (state: RootState, headerView: DataView): string | undefined => {
+  const hdr = parseKuwoHeader(headerView);
+  if (!hdr) {
+    return;
+  }
+
+  const keys = selectFinalKWMv2Keys(state);
+  const lookupKey = kwm2StagingToProductionKey({ id: '', ekey: '', quality: hdr.quality, rid: hdr.rid });
+
+  let ekey: string | undefined;
+  if (hasOwn(keys, lookupKey)) {
+    ekey = keys[lookupKey];
+  }
+
+  return ekey;
 };