golang中DES/ECB/PKCS5Padding的实现

import (
"encoding/base64"
"bytes"
"encoding/binary"
"crypto/des"
"errors"
"log"
)

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)
unpadding := int(origData[length - 1])
return origData[:(length - unpadding)]
}

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

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