78 lines
2.3 KiB
TypeScript
78 lines
2.3 KiB
TypeScript
import {
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AudioMimeType,
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BytesHasPrefix,
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GetArrayBuffer,
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GetCoverFromFile,
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GetMetaFromFile,
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SniffAudioExt
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} from "@/decrypt/utils";
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import {Decrypt as RawDecrypt} from "@/decrypt/raw";
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import {parseBlob as metaParseBlob} from "music-metadata-browser";
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import {DecryptResult} from "@/decrypt/entity";
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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: File, raw_filename: string, _: string): Promise<DecryptResult> {
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const oriData = new Uint8Array(await GetArrayBuffer(file));
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if (!BytesHasPrefix(oriData, MagicHeader)) {
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if (SniffAudioExt(oriData) === "aac") {
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return await RawDecrypt(file, raw_filename, "aac", false)
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}
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throw Error("not a valid kwm file")
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}
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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 = SniffAudioExt(audioData);
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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 metaParseBlob(musicBlob);
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const {title, artist} = GetMetaFromFile(raw_filename, musicMeta.common.title, musicMeta.common.artist)
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return {
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album: musicMeta.common.album,
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picture: GetCoverFromFile(musicMeta),
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file: URL.createObjectURL(musicBlob),
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blob: musicBlob,
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mime,
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title,
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artist,
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ext
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}
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}
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function createMaskFromKey(keyBytes: Uint8Array): Uint8Array {
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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.charCodeAt(i) ^ keyStrTrim.charCodeAt(i)
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}
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return key
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}
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function trimKey(keyRaw: string): string {
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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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