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Encryptor.go
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Encryptor.go
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package kernel
import (
"bytes"
"crypto/aes"
"crypto/sha1"
"encoding/base64"
"encoding/binary"
"encoding/xml"
"fmt"
"github.com/ArtisanCloud/PowerLibs/v3/object"
"github.com/ArtisanCloud/PowerWeChat/v3/src/kernel/support"
"math/rand"
"sort"
"strings"
"time"
)
// Wechat Docs: https://open.work.weixin.qq.com/api/doc/90000/90138/90307
const (
ErrorInvalidSignature = -40001 // 签名验证错误
ErrorParseXml = -40002 // xml/json解析失败
ErrorCalcSignature = -40003 // sha加密生成签名失败
ErrorInvalidAesKey = -40004 // AESKey 非法
ErrorInvalidAppID = -40005 // ReceiveID 校验错误
ErrorEncryptAes = -40006 // AES 加密失败
ErrorDecryptAes = -40007 // AES 解密失败
ErrorInvalidXml = -40008 // 解密后得到的buffer非法
ErrorBase64Encode = -40009 // base64 编码失败
ErrorBase64Decode = -40010 // base64 解码失败
ErrorXmlBuild = -40011 // 生成xml失败
IllegalBuffer = -41003 // Illegal buffer
letterBytes = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
)
type CDATA struct {
Value string `xml:",cdata"`
}
type WeComReplyMsg struct {
XMLName xml.Name `xml:"xml"`
Encrypt CDATA `xml:"Encrypt"`
Signature CDATA `xml:"MsgSignature"`
Timestamp string `xml:"TimeStamp"`
Nonce CDATA `xml:"Nonce"`
}
type WeComRecvMsg struct {
ToUserName string `xml:"ToUserName"`
Encrypt string `xml:"Encrypt"`
AgentID string `xml:"AgentID"`
}
type Encryptor struct {
appID string // App token
token string
aesKey []byte
blockSize int64
aes *support.AES
}
func NewEncryptor(appID, token, aesKey string) (*Encryptor, error) {
var aesKeyByte []byte
var err error
//if aesKey == "" {
// fmt2.Dump("AES Key is empty, this may occur errors when decode callbacks message")
//}
aesKeyByte, err = base64.StdEncoding.DecodeString(aesKey)
if err != nil {
aesKeyByte, err = base64.RawStdEncoding.DecodeString(aesKey)
if err != nil {
return nil, err
}
}
return &Encryptor{
appID: appID,
token: token,
aesKey: aesKeyByte,
blockSize: 32,
aes: &support.AES{},
}, nil
}
// GetToken Get the app token
func (encryptor *Encryptor) GetToken() string {
return encryptor.token
}
func (encryptor *Encryptor) randString(n int) string {
b := make([]byte, n)
for i := range b {
b[i] = letterBytes[rand.Int63()%int64(len(letterBytes))]
}
return string(b)
}
// Encrypt encrypt xml msg and return xml
func (encryptor *Encryptor) Encrypt(msg, nonce, timestamp string) ([]byte, *support.CryptError) {
randStr := encryptor.randString(16)
var buffer bytes.Buffer
buffer.WriteString(randStr)
msgLenBuf := make([]byte, 4)
binary.BigEndian.PutUint32(msgLenBuf, uint32(len(msg)))
buffer.Write(msgLenBuf)
buffer.WriteString(msg)
// TODO 暂时不知道用途
//buffer.WriteString(wxBizMsgCrypt.receiverID)
buffer.WriteString(encryptor.appID)
tmpCiphertext, err := encryptor.aes.Encrypt(buffer.Bytes(), encryptor.aesKey, encryptor.aesKey[:aes.BlockSize])
if err != nil {
return nil, (*support.CryptError)(err)
}
ciphertext := string(tmpCiphertext)
if timestamp == "" {
timestamp = fmt.Sprintf("%d", time.Now().Unix())
}
if nonce == "" {
nonce = object.QuickRandom(10)
}
signature := encryptor.Signature(encryptor.token, timestamp, nonce, ciphertext)
msg4Send := &WeComReplyMsg{
Encrypt: CDATA{Value: ciphertext},
Signature: CDATA{Value: signature},
Timestamp: timestamp,
Nonce: CDATA{Value: nonce},
}
//msg4Send := NewWXBizMsg4Send(ciphertext, signature, timestamp, nonce)
//msg.Marshal()
xmlByte, err2 := xml.Marshal(msg4Send)
if err2 != nil {
return nil, support.NewCryptError(ErrorXmlBuild, err2.Error())
}
return xmlByte, nil
}
// Decrypt decrypt xml msg and return xml
func (encryptor *Encryptor) Decrypt(content []byte, msgSignature, nonce, timestamp string) ([]byte, *support.CryptError) {
var msg4Recv WeComRecvMsg
err := xml.Unmarshal(content, &msg4Recv)
if err != nil {
return nil, support.NewCryptError(ErrorDecryptAes, err.Error())
}
signature := encryptor.Signature(encryptor.token, timestamp, nonce, msg4Recv.Encrypt)
if strings.Compare(signature, msgSignature) != 0 {
return nil, support.NewCryptError(ErrorCalcSignature, "signature not equal")
}
iv := encryptor.aesKey[:aes.BlockSize]
plaintext, cryptErr := encryptor.aes.Decrypt(msg4Recv.Encrypt, encryptor.aesKey, iv)
//plaintext, cryptErr := wxBizMsgCrypt.cbcDecrypter(msg4Recv.Encrypt)
if nil != cryptErr {
return nil, cryptErr
}
textLen := uint32(len(plaintext))
if textLen < 20 {
return nil, support.NewCryptError(IllegalBuffer, "plain is to small 1")
}
//random := plaintext[:16]
msgLen := binary.BigEndian.Uint32(plaintext[16:20])
if textLen < (20 + msgLen) {
return nil, support.NewCryptError(IllegalBuffer, "plain is to small 2")
}
msg := plaintext[20 : 20+msgLen]
//receiverID := plaintext[20+msgLen:]
return msg, nil
}
// Decrypt decrypt xml msg and return xml
func (encryptor *Encryptor) DecryptContent(content string) ([]byte, *support.CryptError) {
iv := encryptor.aesKey[:aes.BlockSize]
plaintext, cryptErr := encryptor.aes.Decrypt(content, encryptor.aesKey, iv)
//plaintext, cryptErr := wxBizMsgCrypt.cbcDecrypter(msg4Recv.Encrypt)
if nil != cryptErr {
return nil, cryptErr
}
textLen := uint32(len(plaintext))
if textLen < 20 {
return nil, support.NewCryptError(IllegalBuffer, "plain is to small 1")
}
//random := plaintext[:16]
msgLen := binary.BigEndian.Uint32(plaintext[16:20])
if textLen < (20 + msgLen) {
return nil, support.NewCryptError(IllegalBuffer, "plain is to small 2")
}
msg := plaintext[20 : 20+msgLen]
//receiverID := plaintext[20+msgLen:]
return msg, nil
}
// VerifyUrl Parsing the official WeChat callbacks validation.
// Wechat Docs: https://work.weixin.qq.com/api/doc/90000/90135/90235
// When adding URLs to the WeChat admin backend, WeChat will trigger a GET request to verify whether the server can process the encrypted information properly, and the uniformMessage needs to be decrypted and returned.
// 在微信管理后台添加URL的时候,微信会触发一条GET请求用于验证服务器能否正常处理加密信息,需要将消息解密出来返回。
// eg: "/app-callbacks?msg_signature=1495c4dfd4958d4e5faf618978ae66943a042f87×tamp=1623292419&nonce=1623324060&echostr=o1XtmVltGmUAqoWee54yd4Q5ZBgrw4%2F9lFo5qdZoVPd1DybzarjuYCfFlR2AFbAcWHwFgmbrVBD%2Bf9910QIF6g%3D%3D"
func (encryptor *Encryptor) VerifyUrl(content string, msgSignature, nonce, timestamp string) ([]byte, *support.CryptError) {
msg4Recv := &WeComRecvMsg{
Encrypt: content,
}
msg4RecvByte, err := xml.Marshal(msg4Recv)
if err != nil {
return nil, support.NewCryptError(ErrorXmlBuild, err.Error())
}
return encryptor.Decrypt(msg4RecvByte, msgSignature, nonce, timestamp)
}
// Signature get sha1
func (encryptor *Encryptor) Signature(token, timestamp, nonce, data string) string {
sortArr := []string{token, timestamp, nonce, data}
sort.Strings(sortArr)
var buffer bytes.Buffer
for _, value := range sortArr {
buffer.WriteString(value)
}
sha := sha1.New()
sha.Write(buffer.Bytes())
signature := fmt.Sprintf("%x", sha.Sum(nil))
return signature
}