wechat_work_crypto

WeChat Work (WeCom) Crypto Library - Pure Rust Implementation

A pure Rust implementation of the WeChat Work (企业微信) message encryption/decryption library, ported from the official C++ SDK.

Features

• ✅ AES-256-CBC encryption/decryption
• ✅ Base64 encoding/decoding
• ✅ SHA1 signature computation
• ✅ XML parsing and generation
• ✅ Message encryption and decryption
• ✅ URL verification for WeChat server callback
• ✅ Full error handling with proper error codes
• ✅ Zero unsafe code
• ✅ Idiomatic Rust API

Installation

Add this to your Cargo.toml:

[dependencies]
wechat_work_crypto = "0.1.0"

Usage

Basic Setup

use wechat_work_crypto::WXBizMsgCrypt;

// Configuration from WeChat Work
let token = "your_token_here";
let encoding_aes_key = "jWmYm7qr5nMoAUwZRjGtBxmz3PL1k2yftF4vsTlMqPS";
let receive_id = "your_corpid_here";

// Initialize the crypto instance
let crypt = WXBizMsgCrypt::new(token, encoding_aes_key, receive_id)?;

Verify URL (Server Verification)

When WeChat Work verifies your server:

let msg_signature = "5c45ff5e21c57e6ad56bac8c868eb9068928468d";
let timestamp = "1409659813";
let nonce = "263014780";
let echo_str = "P9nAzCzyDtyTWESHep1vC5X9xho/qYX3Zpb4yKa9SKld1DsH3Iyt3tP3zNdV+SNh2FvLm0Yc1HlON16aRqv3+A==";

let echo_result = crypt.verify_url(msg_signature, timestamp, nonce, echo_str)?;
println!("Verified: {}", echo_result);

Decrypt Messages

Decrypt messages received from WeChat Work:

let msg_signature = "signature_from_url";
let timestamp = "1409659813";
let nonce = "263014780";
let post_data = r#"<xml>
    <Encrypt><![CDATA[encrypted_content_here]]></Encrypt>
    <MsgSignature><![CDATA[signature]]></MsgSignature>
    <TimeStamp>1409659813</TimeStamp>
    <Nonce><![CDATA[263014780]]></Nonce>
</xml>"#;

let decrypted_msg = crypt.decrypt_msg(msg_signature, timestamp, nonce, post_data)?;
println!("Decrypted: {}", decrypted_msg);

Encrypt Messages

Encrypt messages to send back to WeChat Work:

let reply_msg = r#"<xml>
    <ToUserName><![CDATA[openID]]></ToUserName>
    <FromUserName><![CDATA[gh_123456789]]></FromUserName>
    <CreateTime>1409659813</CreateTime>
    <MsgType><![CDATA[text]]></MsgType>
    <Content><![CDATA[Hello from Rust!]]></Content>
</xml>"#;
let timestamp = "1409659813";
let nonce = "263014780";

let encrypted_xml = crypt.encrypt_msg(reply_msg, timestamp, nonce)?;
println!("Encrypted: {}", encrypted_xml);

Error Codes

The library returns proper error codes matching the official C++ SDK:

Encryption Details

The library implements the WeChat Work encryption protocol:

1. Encryption Format: random(16B) + msg_len(4B) + msg + corpId
2. Random String: 16 random printable ASCII characters
3. Message Length: 4 bytes in network byte order (big-endian)
4. AES-256-CBC: With PKCS7 padding
5. IV: Uses the first 16 bytes of the AES key
6. Signature: SHA1 hash of sorted token + timestamp + nonce + encrypted_msg

Testing

Run the test suite:

cargo test

Run the example:

cargo run

API Reference

WXBizMsgCrypt

Main struct for WeChat Work crypto operations.

Methods

• new(token, encoding_aes_key, receive_id) - Create a new instance
• verify_url(msg_signature, timestamp, nonce, echo_str) - Verify URL
• decrypt_msg(msg_signature, timestamp, nonce, post_data) - Decrypt message
• encrypt_msg(reply_msg, timestamp, nonce) - Encrypt message
• get_xml_field(xml_data, field_name) - Extract field from XML (static method)

WXBizMsgCryptError

Error enum with comprehensive error handling.

Methods

• error_code() - Get the numeric error code

Dependencies

• aes - AES encryption

• cbc - CBC mode of operation

• base64 - Base64 encoding/decoding

• sha1 - SHA1 hashing

• hex - Hex encoding

• rand - Random number generation

• regex - XML parsing

• thiserror - Error handling

License

This implementation follows the same licensing as the original WeChat Work SDK.

Contributing

Contributions are welcome! Please ensure:

• All tests pass
• Code follows Rust best practices
• Documentation is updated
• No unsafe code is introduced