diff --git a/package-lock.json b/package-lock.json
index 72e4aa1..7f54c3b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1722,6 +1722,12 @@
         "@types/node": "*"
       }
     },
+    "@types/crypto-js": {
+      "version": "4.0.1",
+      "resolved": "http://mirrors.cloud.tencent.com/npm/@types%2fcrypto-js/-/crypto-js-4.0.1.tgz",
+      "integrity": "sha512-6+OPzqhKX/cx5xh+yO8Cqg3u3alrkhoxhE5ZOdSEv0DOzJ13lwJ6laqGU0Kv6+XDMFmlnGId04LtY22PsFLQUw==",
+      "dev": true
+    },
     "@types/debug": {
       "version": "4.1.5",
       "resolved": "https://registry.npmjs.org/@types/debug/-/debug-4.1.5.tgz",
diff --git a/package.json b/package.json
index 3aaeec3..f4e520e 100644
--- a/package.json
+++ b/package.json
@@ -31,6 +31,7 @@
     "vue-property-decorator": "^9.1.2"
   },
   "devDependencies": {
+    "@types/crypto-js": "^4.0.1",
     "@vue/cli-plugin-babel": "^4.5.13",
     "@vue/cli-plugin-pwa": "^4.5.13",
     "@vue/cli-plugin-typescript": "^4.5.13",
diff --git a/src/decrypt/entity.ts b/src/decrypt/entity.ts
index 55faead..a76b9f8 100644
--- a/src/decrypt/entity.ts
+++ b/src/decrypt/entity.ts
@@ -9,7 +9,7 @@ export interface DecryptResult {
     ext: string
 
     file: string
-    picture: string
+    picture?: string
 
     message?: string
     rawExt?: string
diff --git a/src/decrypt/ncm.js b/src/decrypt/ncm.js
deleted file mode 100644
index 70f373b..0000000
--- a/src/decrypt/ncm.js
+++ /dev/null
@@ -1,171 +0,0 @@
-import {
-    AudioMimeType,
-    BytesHasPrefix,
-    GetArrayBuffer,
-    GetImageFromURL,
-    GetMetaFromFile,
-    SniffAudioExt, WriteMetaToFlac, WriteMetaToMp3
-} from "@/decrypt/utils.ts";
-import {parseBlob as metaParseBlob} from "music-metadata-browser";
-import jimp from 'jimp';
-
-const CryptoJS = require("crypto-js");
-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, raw_filename, _) {
-    const fileBuffer = await GetArrayBuffer(file);
-    const dataView = new DataView(fileBuffer);
-
-    if (!BytesHasPrefix(new Uint8Array(fileBuffer, 0, 8), MagicHeader))
-        return {status: false, message: "此ncm文件已损坏"};
-
-    const keyDataObj = getKeyData(dataView, fileBuffer, 10);
-    const keyBox = getKeyBox(keyDataObj.data);
-
-    const musicMetaObj = getMetaData(dataView, fileBuffer, keyDataObj.offset);
-    const musicMeta = musicMetaObj.data;
-    let audioOffset = musicMetaObj.offset + dataView.getUint32(musicMetaObj.offset + 5, true) + 13;
-    let audioData = new Uint8Array(fileBuffer, audioOffset);
-
-    let lenAudioData = audioData.length;
-    for (let cur = 0; cur < lenAudioData; ++cur) audioData[cur] ^= keyBox[cur & 0xff];
-
-    if (musicMeta.album === undefined) musicMeta.album = "";
-
-    const artists = [];
-    if (!!musicMeta.artist) musicMeta.artist.forEach(arr => artists.push(arr[0]));
-    const info = GetMetaFromFile(raw_filename, musicMeta.musicName, artists.join("; "))
-    if (artists.length === 0) artists.push(info.artist);
-
-    if (musicMeta.format === undefined) musicMeta.format = SniffAudioExt(audioData);
-
-    const imageInfo = await GetImageFromURL(musicMeta.albumPic);
-
-    const mime = AudioMimeType[musicMeta.format]
-    try {
-        let musicBlob = new Blob([audioData], {type: mime});
-        const originalMeta = await metaParseBlob(musicBlob);
-        let shouldWrite = !originalMeta.common.album && !originalMeta.common.artists && !originalMeta.common.title
-        if (shouldWrite || imageInfo) {
-            while (imageInfo && imageInfo.buffer.byteLength >= 1 << 24) {
-                let img = await jimp.read(Buffer.from(imageInfo.buffer))
-                await img.resize(Math.round(img.getHeight() / 2), jimp.AUTO)
-                imageInfo.buffer = await img.getBufferAsync("image/jpeg")
-            }
-            const newMeta = {title: info.title, artists, album: musicMeta.album, picture: imageInfo?.buffer}
-            if (musicMeta.format === "mp3") {
-                audioData = WriteMetaToMp3(audioData.buffer, newMeta, originalMeta)
-            } else if (musicMeta.format === "flac") {
-                audioData = WriteMetaToFlac(Buffer.from(audioData), newMeta, originalMeta)
-            }
-        }
-    } catch (e) {
-        console.warn("Error while appending cover image to file ", e)
-    }
-
-    const musicData = new Blob([audioData], {type: mime})
-
-    return {
-        status: true,
-        title: info.title,
-        artist: info.artist,
-        ext: musicMeta.format,
-        album: musicMeta.album,
-        picture: imageInfo.url,
-        file: URL.createObjectURL(musicData),
-        mime: mime
-    }
-}
-
-
-function getKeyData(dataView, fileBuffer, offset) {
-    const keyLen = dataView.getUint32(offset, true);
-    offset += 4;
-    const cipherText = new Uint8Array(fileBuffer, offset, keyLen).map(
-        uint8 => uint8 ^ 0x64
-    );
-    offset += keyLen;
-
-    const plainText = CryptoJS.AES.decrypt(
-        {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 {offset: offset, data: result.slice(17)};
-}
-
-function getKeyBox(keyData) {
-    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];
-    });
-}
-
-/**
- * @typedef {Object} MusicMetaType
- * @property {Number} musicId
- * @property {String} musicName
- * @property {[[String, Number]]} artist
- * @property {String} album
- * @property {"flac"|"mp3"} format
- * @property {String} albumPic
- */
-
-function getMetaData(dataView, fileBuffer, offset) {
-    const metaDataLen = dataView.getUint32(offset, true);
-    offset += 4;
-    if (metaDataLen === 0) return {data: {}, offset: offset};
-
-    const cipherText = new Uint8Array(fileBuffer, offset, metaDataLen).map(
-        data => data ^ 0x63
-    );
-    offset += metaDataLen;
-
-    const plainText = CryptoJS.AES.decrypt({
-            ciphertext: CryptoJS.enc.Base64.parse(
-                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 = JSON.parse(plainText.slice(labelIndex + 1));
-    if (plainText.slice(0, labelIndex) === "dj") {
-        result = result.mainMusic;
-    }
-    if (!!result.albumPic && result.albumPic !== "")
-        result.albumPic = result.albumPic.replace("http://", "https://") + "?param=500y500";
-
-    return {data: result, offset: offset};
-}
-
-
diff --git a/src/decrypt/ncm.ts b/src/decrypt/ncm.ts
new file mode 100644
index 0000000..88a5350
--- /dev/null
+++ b/src/decrypt/ncm.ts
@@ -0,0 +1,235 @@
+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<DecryptResult> {
+    return (new NcmDecrypt(await GetArrayBuffer(file), raw_filename)).decrypt()
+}
+
+
+interface NcmMusicMeta {
+    //musicId: number
+    musicName?: string
+    artist?: Array<string | number>[]
+    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(<string>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 {
+            status: true,
+            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()
+    }
+
+
+}
+
+
diff --git a/src/decrypt/utils.ts b/src/decrypt/utils.ts
index 194a836..c2db07d 100644
--- a/src/decrypt/utils.ts
+++ b/src/decrypt/utils.ts
@@ -119,7 +119,7 @@ export interface IMusicMeta {
     picture_desc?: string
 }
 
-export function WriteMetaToMp3(audioData: ArrayBuffer, info: IMusicMeta, original: IAudioMetadata) {
+export function WriteMetaToMp3(audioData: Buffer, info: IMusicMeta, original: IAudioMetadata) {
     const writer = new ID3Writer(audioData);
 
     // reserve original data
diff --git a/src/shims-browser-id3-writer.d.ts b/src/shims-browser-id3-writer.d.ts
index acd09de..48113af 100644
--- a/src/shims-browser-id3-writer.d.ts
+++ b/src/shims-browser-id3-writer.d.ts
@@ -4,7 +4,7 @@ declare module "browser-id3-writer" {
 
         setFrame(name: string, value: string | object | string[])
 
-        addTag(): ArrayBuffer
+        addTag(): Uint8Array
     }
 }