140 lines
4.5 KiB
JavaScript
140 lines
4.5 KiB
JavaScript
const CryptoJS = require("crypto-js");
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const CORE_KEY = CryptoJS.enc.Hex.parse("687a4852416d736f356b496e62617857");
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const META_KEY = CryptoJS.enc.Hex.parse("2331346C6A6B5F215C5D2630553C2728");
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import {AudioMimeType, DetectAudioExt, GetArrayBuffer, GetFileInfo, GetWebImage, WriteMp3Meta} from "./util"
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export async function Decrypt(file, raw_filename, raw_ext) {
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const fileBuffer = await GetArrayBuffer(file);
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const dataView = new DataView(fileBuffer);
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if (dataView.getUint32(0, true) !== 0x4e455443 ||
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dataView.getUint32(4, true) !== 0x4d414446)
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return {status: false, message: "此ncm文件已损坏"};
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const keyDataObj = getKeyData(dataView, fileBuffer, 10);
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const keyBox = getKeyBox(keyDataObj.data);
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const musicMetaObj = getMetaData(dataView, fileBuffer, keyDataObj.offset);
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const musicMeta = musicMetaObj.data;
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let audioOffset = musicMetaObj.offset + dataView.getUint32(musicMetaObj.offset + 5, true) + 13;
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let audioData = new Uint8Array(fileBuffer, audioOffset);
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let lenAudioData = audioData.length;
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for (let cur = 0; cur < lenAudioData; ++cur) audioData[cur] ^= keyBox[cur & 0xff];
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if (musicMeta.album === undefined) musicMeta.album = "";
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const artists = [];
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if (!!musicMeta.artist) musicMeta.artist.forEach(arr => artists.push(arr[0]));
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const info = GetFileInfo(artists.join(" & "), musicMeta.musicName, raw_filename);
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if (artists.length === 0) artists.push(info.artist);
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if (musicMeta.format === undefined) musicMeta.format = DetectAudioExt(audioData, "mp3");
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const imageInfo = await GetWebImage(musicMeta.albumPic);
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if (musicMeta.format === "mp3") audioData = await WriteMp3Meta(
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audioData, artists, info.title, musicMeta.album, imageInfo.buffer, musicMeta.albumPic);
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const mime = AudioMimeType[musicMeta.format];
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const musicData = new Blob([audioData], {type: mime});
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return {
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status: true,
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title: info.title,
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artist: info.artist,
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ext: musicMeta.format,
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album: musicMeta.album,
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picture: imageInfo.url,
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file: URL.createObjectURL(musicData),
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mime: mime
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};
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}
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function getKeyData(dataView, fileBuffer, offset) {
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const keyLen = dataView.getUint32(offset, true);
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offset += 4;
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const cipherText = new Uint8Array(fileBuffer, offset, keyLen).map(
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uint8 => uint8 ^ 0x64
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);
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offset += keyLen;
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const plainText = CryptoJS.AES.decrypt(
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{ciphertext: CryptoJS.lib.WordArray.create(cipherText)},
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CORE_KEY,
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{
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mode: CryptoJS.mode.ECB,
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padding: CryptoJS.pad.Pkcs7
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}
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);
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const result = new Uint8Array(plainText.sigBytes);
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const words = plainText.words;
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const sigBytes = plainText.sigBytes;
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for (let i = 0; i < sigBytes; i++) {
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result[i] = (words[i >>> 2] >>> (24 - (i % 4) * 8)) & 0xff;
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}
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return {offset: offset, data: result.slice(17)};
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}
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function getKeyBox(keyData) {
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const box = new Uint8Array(Array(256).keys());
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const keyDataLen = keyData.length;
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let j = 0;
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for (let i = 0; i < 256; i++) {
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j = (box[i] + j + keyData[i % keyDataLen]) & 0xff;
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[box[i], box[j]] = [box[j], box[i]];
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}
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return box.map((_, i, arr) => {
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i = (i + 1) & 0xff;
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const si = arr[i];
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const sj = arr[(i + si) & 0xff];
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return arr[(si + sj) & 0xff];
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});
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}
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/**
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* @typedef {Object} MusicMetaType
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* @property {Number} musicId
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* @property {String} musicName
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* @property {[[String, Number]]} artist
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* @property {String} album
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* @property {"flac"|"mp3"} format
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* @property {String} albumPic
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*/
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function getMetaData(dataView, fileBuffer, offset) {
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const metaDataLen = dataView.getUint32(offset, true);
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offset += 4;
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if (metaDataLen === 0) return {data: {}, offset: offset};
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const cipherText = new Uint8Array(fileBuffer, offset, metaDataLen).map(
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data => data ^ 0x63
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);
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offset += metaDataLen;
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const plainText = CryptoJS.AES.decrypt({
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ciphertext: CryptoJS.enc.Base64.parse(
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CryptoJS.lib.WordArray.create(cipherText.slice(22)).toString(CryptoJS.enc.Utf8)
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)
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},
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META_KEY,
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{mode: CryptoJS.mode.ECB, padding: CryptoJS.pad.Pkcs7}
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).toString(CryptoJS.enc.Utf8);
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const labelIndex = plainText.indexOf(":");
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let result = JSON.parse(plainText.slice(labelIndex + 1));
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if (plainText.slice(0, labelIndex) === "dj") {
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result = result.mainMusic;
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}
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result.albumPic = result.albumPic.replace("http:", "https:");
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return {data: result, offset: offset};
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}
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