67 lines
2.0 KiB
JavaScript
67 lines
2.0 KiB
JavaScript
import {AudioMimeType, DetectAudioExt, GetArrayBuffer, GetFileInfo, GetMetaCoverURL, IsBytesEqual} from "./util";
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const musicMetadata = require("music-metadata-browser");
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const MagicHeader = [
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0x79, 0x65, 0x65, 0x6C, 0x69, 0x6F, 0x6E, 0x2D,
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0x6B, 0x75, 0x77, 0x6F, 0x2D, 0x74, 0x6D, 0x65,
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]
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const PreDefinedKey = "MoOtOiTvINGwd2E6n0E1i7L5t2IoOoNk"
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export async function Decrypt(file, raw_filename, raw_ext) {
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const oriData = new Uint8Array(await GetArrayBuffer(file));
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if (!IsBytesEqual(MagicHeader, oriData.slice(0, 0x10)))
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return {status: false, message: "Not a valid kwm file!"}
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let fileKey = oriData.slice(0x18, 0x20)
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let mask = createMaskFromKey(fileKey)
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let audioData = oriData.slice(0x400);
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let lenAudioData = audioData.length;
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for (let cur = 0; cur < lenAudioData; ++cur)
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audioData[cur] ^= mask[cur % 0x20];
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const ext = DetectAudioExt(audioData, "mp3");
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const mime = AudioMimeType[ext];
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let musicBlob = new Blob([audioData], {type: mime});
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const musicMeta = await musicMetadata.parseBlob(musicBlob);
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const info = GetFileInfo(musicMeta.common.artist, musicMeta.common.title, raw_filename);
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const imgUrl = GetMetaCoverURL(musicMeta);
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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: ext,
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album: musicMeta.common.album,
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picture: imgUrl,
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file: URL.createObjectURL(musicBlob),
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mime: mime
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}
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}
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function createMaskFromKey(keyBytes) {
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let keyView = new DataView(keyBytes.buffer)
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let keyStr = keyView.getBigUint64(0, true).toString()
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let keyStrTrim = trimKey(keyStr)
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let key = new Uint8Array(32)
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for (let i = 0; i < 32; i++) {
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key[i] = PreDefinedKey[i].charCodeAt() ^ keyStrTrim[i].charCodeAt()
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}
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return key
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}
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function trimKey(keyRaw) {
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let lenRaw = keyRaw.length;
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let out = keyRaw;
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if (lenRaw > 32) {
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out = keyRaw.slice(0, 32)
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} else if (lenRaw < 32) {
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out = keyRaw.padEnd(32, keyRaw)
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}
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return out
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}
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