golang 3des/ecb/cbc/pkcs5 加解密

本人新手，参考文档：

http://blog.studygolang.com/2013/01/go加密解密之des/

http://blog.csdn.net/scybs/article/details/38279159

// DES、3DES加解密示例，用于生产环境请修改代码使之健壮
package main

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

func main() {
	test3Des()
}

func test3Des() {
	key, err := base64.StdEncoding.DecodeString("b93e24738d364ad38047a97d6a8ad63c")
	result, err := TripleDesECBEncrypt([]byte("一直都在poiuy123"), key)
	if err != nil {
		panic(err)
	}
	fmt.Println(base64.StdEncoding.EncodeToString(result))
	origData, err := TripleDesECBDecrypt(result, key)
	if err != nil {
		panic(err)
	}
	fmt.Println(string(origData))
}

// 3DES加密
func TripleDesCBCEncrypt(origData, key []byte) ([]byte, error) {
	block, err := des.NewTripleDESCipher(key)
	if err != nil {
		return nil, err
	}
	origData = PKCS5Padding(origData, block.BlockSize())
	// origData = ZeroPadding(origData, block.BlockSize())
	blockMode := cipher.NewCBCEncrypter(block, key[:8])
	crypted := make([]byte, len(origData))
	blockMode.CryptBlocks(crypted, origData)
	return crypted, nil
}

// 3DES解密
func TripleDesCBCDecrypt(crypted, key []byte) ([]byte, error) {
	block, err := des.NewTripleDESCipher(key)
	if err != nil {
		return nil, err
	}
	blockMode := cipher.NewCBCDecrypter(block, key[:8])
	origData := make([]byte, len(crypted))
	// origData := crypted
	blockMode.CryptBlocks(origData, crypted)
	origData = PKCS5UnPadding(origData)
	// origData = ZeroUnPadding(origData)
	return origData, nil
}

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

func PKCS5UnPadding(origData []byte) []byte {
	length := len(origData)
	// 去掉最后一个字节 unpadding 次
	unpadding := int(origData[length-1])
	return origData[:(length - unpadding)]
}

func TripleDesECBEncrypt(origData, key []byte) ([]byte, error) {
	block, err := des.NewTripleDESCipher(key)
	if err != nil {
		return nil, err
	}
	bs := block.BlockSize()
	origData = PKCS5Padding(origData, bs)
	if len(origData)%bs != 0 {
		return nil, errors.New("Need a multiple of the blocksize")
	}
	out := make([]byte, len(origData))
	dst := out
	for len(origData) > 0 {
		block.Encrypt(dst, origData[:bs])
		origData = origData[bs:]
		dst = dst[bs:]
	}
	return out, nil
}

func TripleDesECBDecrypt(crypted, key []byte) ([]byte, error) {
	block, err := des.NewTripleDESCipher(key)
	if err != nil {
		return nil, err
	}
	bs := block.BlockSize()
	if len(crypted)%bs != 0 {
		return nil, errors.New("crypto/cipher: input not full blocks")
	}
	out := make([]byte, len(crypted))
	dst := out
	for len(crypted) > 0 {
		block.Decrypt(dst, crypted[:bs])
		crypted = crypted[bs:]
		dst = dst[bs:]
	}
	out = PKCS5UnPadding(out)
	return out, nil
}