des ecb mode in golang

des.go

package main

import (
	"bytes"
	"crypto/des"
	"errors"
)

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 ZeroPadding(ciphertext []byte, blockSize int) []byte {
	padding := blockSize - len(ciphertext)%blockSize
	padtext := bytes.Repeat([]byte{0}, padding)
	return append(ciphertext, padtext...)
}

func ZeroUnPadding(origData []byte) []byte {
	return bytes.TrimFunc(origData,
		func(r rune) bool {
			return r == rune(0)
		})
}

func DesEncrypt(src, key []byte) ([]byte, error) {
	block, err := des.NewCipher(key)
	if err != nil {
		return nil, err
	}
	bs := block.BlockSize()
	src = ZeroPadding(src, bs)
	// 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 = ZeroUnPadding(out)
	// out = PKCS5UnPadding(out)
	return out, nil
}

des_test.go

package main

import (
	"fmt"
	"testing"
)

func TestDesEncrypt(t *testing.T) {
	key := []byte("5e8487e6")
	origtext := []byte("hello world123563332")

	erytext, err := DesEncrypt(origtext, key)
	if err != nil {
		t.Fatal(err)
	}
	fmt.Printf("%v\n", erytext)
	destext, err2 := DesDecrypt(erytext, key)
	if err2 != nil {
		t.Fatal(err2)
	}
	fmt.Println(string(destext))
	fmt.Println(len(origtext), len(string(destext)))
	fmt.Println(string(origtext) == string(destext))
}

test.sh

go test . -v