import { AudioMimeType, BytesHasPrefix, GetArrayBuffer, GetImageFromURL, GetMetaFromFile, IMusicMeta, SniffAudioExt, WriteMetaToFlac, WriteMetaToMp3, } from '@/decrypt/utils'; import { parseBlob as metaParseBlob } from 'music-metadata-browser'; import jimp from 'jimp'; import AES from 'crypto-js/aes'; import PKCS7 from 'crypto-js/pad-pkcs7'; import ModeECB from 'crypto-js/mode-ecb'; import WordArray from 'crypto-js/lib-typedarrays'; import Base64 from 'crypto-js/enc-base64'; import EncUTF8 from 'crypto-js/enc-utf8'; import EncHex from 'crypto-js/enc-hex'; import { DecryptResult } from '@/decrypt/entity'; const CORE_KEY = EncHex.parse('687a4852416d736f356b496e62617857'); const META_KEY = EncHex.parse('2331346C6A6B5F215C5D2630553C2728'); const MagicHeader = [0x43, 0x54, 0x45, 0x4e, 0x46, 0x44, 0x41, 0x4d]; export async function Decrypt(file: File, raw_filename: string, _: string): Promise { return new NcmDecrypt(await GetArrayBuffer(file), raw_filename).decrypt(); } interface NcmMusicMeta { //musicId: number musicName?: string; artist?: Array[]; format?: string; album?: string; albumPic?: string; } interface NcmDjMeta { mainMusic: NcmMusicMeta; } class NcmDecrypt { raw: ArrayBuffer; view: DataView; offset: number = 0; filename: string; format: string = ''; mime: string = ''; audio?: Uint8Array; blob?: Blob; oriMeta?: NcmMusicMeta; newMeta?: IMusicMeta; image?: { mime: string; buffer: ArrayBuffer; url: string }; constructor(buf: ArrayBuffer, filename: string) { const prefix = new Uint8Array(buf, 0, 8); if (!BytesHasPrefix(prefix, MagicHeader)) throw Error('此ncm文件已损坏'); this.offset = 10; this.raw = buf; this.view = new DataView(buf); this.filename = filename; } _getKeyData(): Uint8Array { const keyLen = this.view.getUint32(this.offset, true); this.offset += 4; const cipherText = new Uint8Array(this.raw, this.offset, keyLen).map((uint8) => uint8 ^ 0x64); this.offset += keyLen; const plainText = AES.decrypt( // @ts-ignore { ciphertext: WordArray.create(cipherText) }, CORE_KEY, { mode: ModeECB, padding: PKCS7 }, ); const result = new Uint8Array(plainText.sigBytes); const words = plainText.words; const sigBytes = plainText.sigBytes; for (let i = 0; i < sigBytes; i++) { result[i] = (words[i >>> 2] >>> (24 - (i % 4) * 8)) & 0xff; } return result.slice(17); } _getKeyBox(): Uint8Array { const keyData = this._getKeyData(); const box = new Uint8Array(Array(256).keys()); const keyDataLen = keyData.length; let j = 0; for (let i = 0; i < 256; i++) { j = (box[i] + j + keyData[i % keyDataLen]) & 0xff; [box[i], box[j]] = [box[j], box[i]]; } return box.map((_, i, arr) => { i = (i + 1) & 0xff; const si = arr[i]; const sj = arr[(i + si) & 0xff]; return arr[(si + sj) & 0xff]; }); } _getMetaData(): NcmMusicMeta { const metaDataLen = this.view.getUint32(this.offset, true); this.offset += 4; if (metaDataLen === 0) return {}; const cipherText = new Uint8Array(this.raw, this.offset, metaDataLen).map((data) => data ^ 0x63); this.offset += metaDataLen; WordArray.create(); const plainText = AES.decrypt( // @ts-ignore { ciphertext: Base64.parse( // @ts-ignore WordArray.create(cipherText.slice(22)).toString(EncUTF8), ), }, META_KEY, { mode: ModeECB, padding: PKCS7 }, ).toString(EncUTF8); const labelIndex = plainText.indexOf(':'); let result: NcmMusicMeta; if (plainText.slice(0, labelIndex) === 'dj') { const tmp: NcmDjMeta = JSON.parse(plainText.slice(labelIndex + 1)); result = tmp.mainMusic; } else { result = JSON.parse(plainText.slice(labelIndex + 1)); } if (!!result.albumPic) { result.albumPic = result.albumPic.replace('http://', 'https://') + '?param=500y500'; } return result; } _getAudio(keyBox: Uint8Array): Uint8Array { this.offset += this.view.getUint32(this.offset + 5, true) + 13; const audioData = new Uint8Array(this.raw, this.offset); let lenAudioData = audioData.length; for (let cur = 0; cur < lenAudioData; ++cur) audioData[cur] ^= keyBox[cur & 0xff]; return audioData; } async _buildMeta() { if (!this.oriMeta) throw Error('invalid sequence'); const info = GetMetaFromFile(this.filename, this.oriMeta.musicName); // build artists let artists: string[] = []; if (!!this.oriMeta.artist) { this.oriMeta.artist.forEach((arr) => artists.push(arr[0])); } if (artists.length === 0 && !!info.artist) { artists = info.artist .split(',') .map((val) => val.trim()) .filter((val) => val != ''); } if (this.oriMeta.albumPic) try { this.image = await GetImageFromURL(this.oriMeta.albumPic); while (this.image && this.image.buffer.byteLength >= 1 << 24) { let img = await jimp.read(Buffer.from(this.image.buffer)); await img.resize(Math.round(img.getHeight() / 2), jimp.AUTO); this.image.buffer = await img.getBufferAsync('image/jpeg'); } } catch (e) { console.log('get cover image failed', e); } this.newMeta = { title: info.title, artists, album: this.oriMeta.album, picture: this.image?.buffer }; } async _writeMeta() { if (!this.audio || !this.newMeta) throw Error('invalid sequence'); if (!this.blob) this.blob = new Blob([this.audio], { type: this.mime }); const ori = await metaParseBlob(this.blob); let shouldWrite = !ori.common.album && !ori.common.artists && !ori.common.title; if (shouldWrite || this.newMeta.picture) { if (this.format === 'mp3') { this.audio = WriteMetaToMp3(Buffer.from(this.audio), this.newMeta, ori); } else if (this.format === 'flac') { this.audio = WriteMetaToFlac(Buffer.from(this.audio), this.newMeta, ori); } else { console.info(`writing meta for ${this.format} is not being supported for now`); return; } this.blob = new Blob([this.audio], { type: this.mime }); } } gatherResult(): DecryptResult { if (!this.newMeta || !this.blob) throw Error('bad sequence'); return { title: this.newMeta.title, artist: this.newMeta.artists?.join('; '), ext: this.format, album: this.newMeta.album, picture: this.image?.url, file: URL.createObjectURL(this.blob), blob: this.blob, mime: this.mime, }; } async decrypt() { const keyBox = this._getKeyBox(); this.oriMeta = this._getMetaData(); this.audio = this._getAudio(keyBox); this.format = this.oriMeta.format || SniffAudioExt(this.audio); this.mime = AudioMimeType[this.format]; await this._buildMeta(); try { await this._writeMeta(); } catch (e) { console.warn('write meta data failed', e); } return this.gatherResult(); } }