加解密包

Author: gowso

crypto.go

@@ -1,11 +1,164 @@
 package godingtalk
 
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/base64"
+	"encoding/binary"
+	"errors"
+	"math/rand"
+	r "math/rand"
+	"sort"
+	"time"
+)
+
+const (
+	AES_ENCODE_KEY_LENGTH = 43
+)
+
+var DefaultDingtalkCrypto *Crypto
+
 type Crypto struct {
 	Token    string
 	AesKey   string
 	SuiteKey string
+	block    cipher.Block
+	bkey     []byte
+}
+
+/*
+	token		数据签名需要用到的token，ISV(服务提供商)推荐使用注册套件时填写的token，普通企业可以随机填写
+	aesKey  	数据加密密钥。用于回调数据的加密，长度固定为43个字符，从a-z, A-Z, 0-9共62个字符中选取,您可以随机生成，ISV(服务提供商)推荐使用注册套件时填写的EncodingAESKey
+	suiteKey	一般使用corpID
+*/
+func NewCrypto(token, aesKey, suiteKey string) (c *Crypto) {
+	c = &Crypto{
+		Token:    token,
+		AesKey:   aesKey,
+		SuiteKey: suiteKey,
+	}
+	if len(c.AesKey) != AES_ENCODE_KEY_LENGTH {
+		panic("不合法的aeskey")
+	}
+	var err error
+	c.bkey, err = base64.StdEncoding.DecodeString(aesKey + "=")
+	if err != nil {
+		panic(err.Error())
+	}
+	c.block, err = aes.NewCipher(c.bkey)
+	if err != nil {
+		panic(err.Error())
+	}
+	return c
+}
+
+/*
+	signature: 签名字符串
+	timeStamp: 时间戳
+	nonce: 随机字符串
+	secretStr: 密文
+	返回: 解密后的明文
+*/
+func (c *Crypto) DecryptMsg(signature, timeStamp, nonce, secretStr string) (string, error) {
+	if !c.VerifySignature(c.Token, timeStamp, nonce, secretStr, signature) {
+		return "", errors.New("签名不匹配")
+	}
+	decode, err := base64.StdEncoding.DecodeString(secretStr)
+	if err != nil {
+		return "", err
+	}
+	if len(decode) < aes.BlockSize {
+		return "", errors.New("密文太短啦")
+	}
+	blockMode := cipher.NewCBCDecrypter(c.block, c.bkey[:c.block.BlockSize()])
+	plantText := make([]byte, len(decode))
+	blockMode.CryptBlocks(plantText, decode)
+	plantText = PKCS7UnPadding(plantText)
+	size := binary.BigEndian.Uint32(plantText[16 : 16+4])
+	plantText = plantText[16+4:]
+	cropid := plantText[size:]
+	if string(cropid) != c.SuiteKey {
+		return "", errors.New("CropID不正确")
+	}
+	return string(plantText[:size]), nil
+}
+
+func PKCS7UnPadding(plantText []byte) []byte {
+	length := len(plantText)
+	unpadding := int(plantText[length-1])
+	return plantText[:(length - unpadding)]
 }
 
-func (c *Crypto) Encrypt(str string) {
+/*
+	replyMsg: 明文字符串
+	timeStamp: 时间戳
+	nonce: 随机字符串
+	返回: 密文,签名字符串
+*/
+func (c *Crypto) EncryptMsg(replyMsg, timeStamp, nonce string) (string, string, error) {
+	//原生消息体长度
+	size := make([]byte, 4)
+	binary.BigEndian.PutUint32(size, uint32(len(replyMsg)))
+	replyMsg = c.RandomString(16) + string(size) + replyMsg + c.SuiteKey
+	plantText := PKCS7Padding([]byte(replyMsg), c.block.BlockSize())
+	if len(plantText)%aes.BlockSize != 0 {
+		return "", "", errors.New("消息体大小不为16的倍数")
+	}
+
+	blockMode := cipher.NewCBCEncrypter(c.block, c.bkey[:c.block.BlockSize()])
+	ciphertext := make([]byte, len(plantText))
+	blockMode.CryptBlocks(ciphertext, plantText)
+	outStr := base64.StdEncoding.EncodeToString(ciphertext)
+	sigStr := c.GenerateSignature(c.Token, timeStamp, nonce, string(outStr))
+	return string(outStr), sigStr, nil
+}
+
+func PKCS7Padding(ciphertext []byte, blockSize int) []byte {
+	padding := blockSize - len(ciphertext)%blockSize
+	padtext := bytes.Repeat([]byte{byte(padding)}, padding)
+	return append(ciphertext, padtext...)
+}
+
+// 数据签名
+func (c *Crypto) GenerateSignature(token, timeStamp, nonce, secretStr string) string {
+	// 先将参数值进行排序
+	params := make([]string, 0)
+	params = append(params, token)
+	params = append(params, secretStr)
+	params = append(params, timeStamp)
+	params = append(params, nonce)
+	sort.Strings(params)
+	return sha1Sign(params[0] + params[1] + params[2] + params[3])
+}
+
+// 校验数据签名
+func (c *Crypto) VerifySignature(token, timeStamp, nonce, secretStr, sigture string) bool {
+	return c.GenerateSignature(token, timeStamp, nonce, secretStr) == sigture
+}
 
+func (c *Crypto) RandomString(n int, alphabets ...byte) string {
+	const alphanum = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+	var bytes = make([]byte, n)
+	var randby bool
+	if num, err := rand.Read(bytes); num != n || err != nil {
+		r.Seed(time.Now().UnixNano())
+		randby = true
+	}
+	for i, b := range bytes {
+		if len(alphabets) == 0 {
+			if randby {
+				bytes[i] = alphanum[r.Intn(len(alphanum))]
+			} else {
+				bytes[i] = alphanum[b%byte(len(alphanum))]
+			}
+		} else {
+			if randby {
+				bytes[i] = alphabets[r.Intn(len(alphabets))]
+			} else {
+				bytes[i] = alphabets[b%byte(len(alphabets))]
+			}
+		}
+	}
+	return string(bytes)
 }