@weixin-ts/cdn

WeChat CDN upload/download with AES-128-ECB encryption. Cross-platform using WebCrypto API.

Disclaimer: This project is an unofficial SDK for the WeChat iLink Bot API. It is not affiliated with, endorsed by, or supported by Tencent or WeChat. Use it at your own risk and ensure compliance with applicable terms of service.

Features

• AES-128-ECB: Encrypt/decrypt using WebCrypto (no node:crypto dependency)
• Upload pipeline: Full flow from file → hash → encrypt → CDN upload
• Download + decrypt: Fetch and decrypt media from WeChat CDN
• Cross-platform: Works in Node.js 18+, Deno, Bun, and browsers
• Zero dependencies: Pure Web standard APIs

Install

pnpm add @weixin-ts/cdn

Usage

Upload Media

import { uploadMedia } from '@weixin-ts/cdn'

const result = await uploadMedia({
  file: imageBuffer, // Uint8Array or ArrayBuffer
  toUserId: 'recipient_user_id',
  mediaType: 'image', // 'image' | 'video' | 'file' | 'voice'
  apiOptions: {
    baseUrl: 'https://ilinkai.weixin.qq.com',
    token: 'YOUR_BOT_TOKEN',
  },
  cdnBaseUrl: 'https://novac2c.cdn.weixin.qq.com/c2c',
})

// Use result.downloadParam in message construction
console.log(result.filekey, result.aesKeyHex)

Download Media

import { downloadMedia } from '@weixin-ts/cdn'

// From an incoming message
const decrypted = await downloadMedia({
  media: message.item_list[0].image_item.media,
  aesKeyHex: message.item_list[0].image_item.aeskey,
})

Low-level AES-ECB

import { decryptAesEcb, encryptAesEcb } from '@weixin-ts/cdn'

const key = crypto.getRandomValues(new Uint8Array(16))
const encrypted = await encryptAesEcb(data, key)
const decrypted = await decryptAesEcb(encrypted, key)

API

uploadMedia(options) → UploadedMedia

Full upload pipeline: hash → encrypt → request URL → upload to CDN.

downloadMedia(options) → Uint8Array

Download and decrypt a media file from CDN.

encryptAesEcb(plaintext, key) → Uint8Array

Encrypt data using AES-128-ECB with PKCS7 padding.

decryptAesEcb(ciphertext, key) → Uint8Array

Decrypt AES-128-ECB encrypted data, removing PKCS7 padding.

Utilities

• aesEcbPaddedSize(rawSize) — Calculate ciphertext size
• md5Hex(data) — Compute MD5 hash (hex string)
• randomBytes(length) — Cryptographic random bytes
• toHex(bytes) / fromHex(hex) — Hex conversion
• toBase64(bytes) / fromBase64(str) — Base64 conversion

Related Packages

• @weixin-ts/bot — Main bot SDK

License

MIT