feat(decrypt/kwm): support raw .acc

src/decrypt/kwm.ts

@@ -0,0 +1,73 @@
+import {GetFileInfo, GetMetaCoverURL} from "./util";
+import {AudioMimeType, BytesHasPrefix, GetArrayBuffer, SniffAudioExt} from "@/decrypt/utils.ts";
+import {Decrypt as RawDecrypt} from "@/decrypt/raw.ts";
+
+import {parseBlob as metaParseBlob} from "music-metadata-browser";
+
+const MagicHeader = [
+    0x79, 0x65, 0x65, 0x6C, 0x69, 0x6F, 0x6E, 0x2D,
+    0x6B, 0x75, 0x77, 0x6F, 0x2D, 0x74, 0x6D, 0x65,
+]
+const PreDefinedKey = "MoOtOiTvINGwd2E6n0E1i7L5t2IoOoNk"
+
+export async function Decrypt(file: File, raw_filename: string, _: string) {
+    const oriData = new Uint8Array(await GetArrayBuffer(file));
+    if (!BytesHasPrefix(oriData, MagicHeader)) {
+        if (SniffAudioExt(oriData) === "aac") {
+            return await RawDecrypt(file, raw_filename, "aac", true)
+        }
+        return {status: false, message: "Not a valid kwm file!"}
+    }
+
+    let fileKey = oriData.slice(0x18, 0x20)
+    let mask = createMaskFromKey(fileKey)
+    let audioData = oriData.slice(0x400);
+    let lenAudioData = audioData.length;
+    for (let cur = 0; cur < lenAudioData; ++cur)
+        audioData[cur] ^= mask[cur % 0x20];
+
+
+    const ext = SniffAudioExt(audioData);
+    const mime = AudioMimeType[ext];
+    let musicBlob = new Blob([audioData], {type: mime});
+
+    const musicMeta = await metaParseBlob(musicBlob);
+    const info = GetFileInfo(musicMeta.common.artist, musicMeta.common.title, raw_filename);
+
+    const imgUrl = GetMetaCoverURL(musicMeta);
+
+    return {
+        status: true,
+        title: info.title,
+        artist: info.artist,
+        ext: ext,
+        album: musicMeta.common.album,
+        picture: imgUrl,
+        file: URL.createObjectURL(musicBlob),
+        mime: mime
+    }
+}
+
+
+function createMaskFromKey(keyBytes: Uint8Array): Uint8Array {
+    let keyView = new DataView(keyBytes.buffer)
+    let keyStr = keyView.getBigUint64(0, true).toString()
+    let keyStrTrim = trimKey(keyStr)
+    let key = new Uint8Array(32)
+    for (let i = 0; i < 32; i++) {
+        key[i] = PreDefinedKey.charCodeAt(i) ^ keyStrTrim.charCodeAt(i)
+    }
+    return key
+}
+
+
+function trimKey(keyRaw: string): string {
+    let lenRaw = keyRaw.length;
+    let out = keyRaw;
+    if (lenRaw > 32) {
+        out = keyRaw.slice(0, 32)
+    } else if (lenRaw < 32) {
+        out = keyRaw.padEnd(32, keyRaw)
+    }
+    return out
+}