package shadow

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
)

func AesEncryptCBC(origData []byte, key []byte) []byte {
	block, _ := aes.NewCipher(key)
	blockSize := block.BlockSize()
	origData = pkcs5Padding(origData, blockSize)
	blockMode := cipher.NewCBCEncrypter(block, key[:blockSize])
	encrypted := make([]byte, len(origData))
	blockMode.CryptBlocks(encrypted, origData)
	return encrypted
}
func AesDecryptCBC(encrypted []byte, key []byte) []byte {
	block, _ := aes.NewCipher(key)
	blockSize := block.BlockSize()
	blockMode := cipher.NewCBCDecrypter(block, key[:blockSize])
	decrypted := make([]byte, len(encrypted))
	blockMode.CryptBlocks(decrypted, encrypted)
	decrypted = pkcs5UnPadding(decrypted)
	return decrypted
}
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)]
}