crypto.go

package goex

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

// ======================== DES CBC =======================

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

func DesCBCDecrypt(crypted, key []byte) ([]byte, error) {
	block, err := des.NewCipher(key)
	if err != nil {
		return nil, err
	}
	blockMode := cipher.NewCBCDecrypter(block, key)
	origData := crypted
	blockMode.CryptBlocks(origData, crypted)
	origData = PKCS5UnPadding(origData)
	//origData = ZeroUnPadding(origData)
	return origData, nil
}

// ======================== DES ECB ========================

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

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

// =========================== DES3 CBC =========================

func Des3CBCEncrypt(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
}

func Des3CBCDecrypt(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))
	blockMode.CryptBlocks(origData, crypted)
	origData = PKCS5UnPadding(origData)
	//origData = ZeroUnPadding(origData)
	return origData, nil
}

// =========================== DES3 ECB  ==========================

func Des3ECBEncrypt(data, key []byte) ([]byte, error) {
	block, err := des.NewTripleDESCipher(key)
	if err != nil {
		return nil, err
	}
	bs := block.BlockSize()
	data = PKCS5Padding(data, bs)
	//data = ZeroPadding(data, bs)
	if len(data)%bs != 0 {
		return nil, errors.New("Need a multiple of the blocksize")
	}
	out := make([]byte, len(data))
	dst := out
	for len(data) > 0 {
		block.Encrypt(dst, data[:bs])
		data = data[bs:]
		dst = dst[bs:]
	}
	return out, nil
}

func Des3ECBDecrypt(data []byte, key []byte) ([]byte, error) {
	block, err := des.NewTripleDESCipher(key)
	if err != nil {
		return nil, err
	}
	bs := block.BlockSize()
	if len(data)%bs != 0 {
		return nil, errors.New("crypto/cipher: input not full blocks")
	}
	out := make([]byte, len(data))
	dst := out
	for len(data) > 0 {
		block.Decrypt(dst, data[:bs])
		data = data[bs:]
		dst = dst[bs:]
	}
	out = PKCS5UnPadding(out)
	//out = ZeroUnPadding(out)
	return out, nil
}

// ============================= util =============================

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.TrimRightFunc(origData, func(r rune) bool {
		return r == rune(0)
	})
}

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)]
}