des_cbc_padding.go

package main

import (
	"bytes"
	"crypto/cipher"
	"crypto/des"
	"encoding/base64"
)

type Decrypter struct {
	Ekey []byte // 加密 key
	Ikey []byte // 校验 key
}

func NewDecrypter(ekey, ikey []byte) *Decrypter {
	return &Decrypter{
		Ekey: ekey,
		Ikey: ikey,
	}
}

func (d *Decrypter) Decode(src string) (text string, err error) {
	data, err := base64.StdEncoding.DecodeString(src)
	if err != nil {
		return
	}

	block, err := des.NewTripleDESCipher(d.Ekey)
	if err != nil {
		return
	}

	ci := cipher.NewCBCDecrypter(block, d.Ikey)
	dst := make([]byte, len(data))
	ci.CryptBlocks(dst, data)
	text = string(dst)
	return
}

func (d *Decrypter) Encode(src string) (text string, err error) {
	block, err := des.NewTripleDESCipher(d.Ekey)
	if err != nil {
		return
	}

	data := []byte(src)
	data = PKCS5Padding(data, block.BlockSize())
	ci := cipher.NewCBCEncrypter(block, d.Ikey)
	dst := make([]byte, len(data))
	ci.CryptBlocks(dst, data)
	text = base64.StdEncoding.EncodeToString(dst)
	return
}

func PKCS5Padding(ciphertext []byte, blockSize int) []byte {
	padding := blockSize - len(ciphertext)%blockSize
	padtext := bytes.Repeat([]byte{byte(padding)}, padding)
	return append(ciphertext, padtext...)
}

func main() {
	dec := NewDecrypter([]byte("liuyunqiang@lx100$#365#$"), []byte("01234567"))
	text, _ := dec.Decode("U4UwyX30n0E=")
	println(text)

	text, _ = dec.Encode("123456")
	println(text)
}