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crypto.go
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crypto.go
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package dingtalk
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/sha1"
"encoding/base64"
"encoding/binary"
"errors"
"fmt"
"math/rand"
r "math/rand"
"sort"
"time"
)
const (
AES_ENCODE_KEY_LENGTH = 43
)
var DefaultDingtalkCrypto *Crypto
/*
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)]
}
/*
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)
}
//////////////////////////////////
func sha1Sign(s string) string {
// The pattern for generating a hash is `sha1.New()`,
// `sha1.Write(bytes)`, then `sha1.Sum([]byte{})`.
// Here we start with a new hash.
h := sha1.New()
// `Write` expects bytes. If you have a string `s`,
// use `[]byte(s)` to coerce it to bytes.
h.Write([]byte(s))
// This gets the finalized hash result as a byte
// slice. The argument to `Sum` can be used to append
// to an existing byte slice: it usually isn't needed.
bs := h.Sum(nil)
// SHA1 values are often printed in hex, for example
// in git commits. Use the `%x` format verb to convert
// a hash results to a hex string.
return fmt.Sprintf("%x", bs)
}