import { AudioMimeType, BytesHasPrefix, GetArrayBuffer, GetImageFromURL, GetMetaFromFile, IMusicMeta, SniffAudioExt, WriteMetaToFlac, WriteMetaToMp3 } from "@/decrypt/utils.ts"; import {parseBlob as metaParseBlob} from "music-metadata-browser"; import jimp from 'jimp'; import CryptoJS from "crypto-js"; import {DecryptResult} from "@/decrypt/entity"; const CORE_KEY = CryptoJS.enc.Hex.parse("687a4852416d736f356b496e62617857"); const META_KEY = CryptoJS.enc.Hex.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 = CryptoJS.AES.decrypt( // @ts-ignore {ciphertext: CryptoJS.lib.WordArray.create(cipherText)}, CORE_KEY, {mode: CryptoJS.mode.ECB, padding: CryptoJS.pad.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; const plainText = CryptoJS.AES.decrypt( //@ts-ignore { ciphertext: CryptoJS.enc.Base64.parse( //@ts-ignore CryptoJS.lib.WordArray.create(cipherText.slice(22)).toString(CryptoJS.enc.Utf8) ) }, META_KEY, {mode: CryptoJS.mode.ECB, padding: CryptoJS.pad.Pkcs7} ).toString(CryptoJS.enc.Utf8); 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) 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), 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() } }