package main

import (
	"bytes"
	"encoding/hex"
	"fmt"
)

func main() {
    
    
	data := []byte("ReganYue")
	encrypt_msg := EnCrypt("123", data)
	fmt.Println("encrypt_msg = ", encrypt_msg)
	fmt.Printf("%x\n", encrypt_msg)
	fmt.Println(hex.EncodeToString(encrypt_msg))
	decrypt_msg := DeCrypt("123", encrypt_msg)
	fmt.Println("decrypt_msg = ", string(decrypt_msg))
}

//加密
func EnCrypt(key string, data []byte) []byte {
    
    
	sum := 0
	for i := 0; i < len(key); i++ {
    
    
		sum = sum + int(key[i])
	}
	//对待加密的明文进行填充
	pad := PaddingText(data, len(key))
	for i := 0; i < len(pad); i++ {
    
    
		pad[i] = pad[i] + byte(sum)
	}
	return pad
}

//解密
func DeCrypt(key string, cipherTxt []byte) []byte {
    
    
	sum := 0
	for i := 0; i < len(key); i++ {
    
    
		sum = sum + int(key[i])
	}
	//对待解密的明文进行解密
	for i := 0; i < len(cipherTxt); i++ {
    
    
		cipherTxt[i] = cipherTxt[i] - byte(sum)
	}
	//去除尾部填充数据
	p := UnPaddingText(cipherTxt)
	return p
}
//填充最后一个分组
//src:待填充的明文
//blockSize:分组大小
func PaddingText(src []byte, blockSize int) []byte {
    
    
	//求出最后一个分组需要填充的字节数
	padding := blockSize - len(src)%blockSize//3
	// [3,3,3]
	padText := bytes.Repeat([]byte{
    
    byte(padding)}, padding)
	//将填充数据拼接到明文后面
	nextText := append(src, padText...)
	return nextText
}

//去除尾部填充数据
func UnPaddingText(src []byte) []byte {
    
    
	len := len(src)
	number := int(src[len-1])
	newText := src[:len-number]
	return newText
}


//ciphertext:待填充的明文  blocksize:每个块的大小
func ZeroPadding(ciphertext []byte, blocksize int) []byte {
    
    
	//计算需要填充几个字节
	padding := blocksize - len(ciphertext)%blocksize
	padtext := bytes.Repeat([]byte{
    
    0}, padding)
	return append(ciphertext, padtext...)
}

//去除尾部填充数据
func ZeroUnPadding(origdata []byte) []byte {
    
    
	return bytes.TrimRightFunc(origdata, func (r rune) bool {
    
    
		return r == rune(0)
	})
}