[go] aes256 cbc 암호화 복호화

PKCS5Padding

base64:

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"encoding/base64"
	"fmt"
)

func AESEncrypt(src string, key []byte, iv string) string {
	block, err := aes.NewCipher(key)
	if err != nil {
		fmt.Println("key error1", err)
	}
	if src == "" {
		fmt.Println("plain content empty")
	}
	ecb := cipher.NewCBCEncrypter(block, []byte(iv))
	content := []byte(src)
	content = PKCS5Padding(content, block.BlockSize())
	crypted := make([]byte, len(content))
	ecb.CryptBlocks(crypted, content)

	return base64.StdEncoding.EncodeToString(crypted)
}

func AESDecrypt(cryptedStr string, key []byte, iv string) []byte {
	encryptedData, _ := base64.StdEncoding.DecodeString(cryptedStr)
	block, err := aes.NewCipher(key)
	if err != nil {
		fmt.Println("key error1", err)
	}
	if len(encryptedData) == 0 {
		fmt.Println("plain content empty")
	}
	ecb := cipher.NewCBCDecrypter(block, []byte(iv))
	decrypted := make([]byte, len(encryptedData))
	ecb.CryptBlocks(decrypted, encryptedData)

	return PKCS5Trimming(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 PKCS5Trimming(encrypt []byte) []byte {
	padding := encrypt[len(encrypt)-1]
	return encrypt[:len(encrypt)-int(padding)]
}

hex:

func Ase256Encode(plaintext string, key string, iv string, blockSize int) string {
	bKey := []byte(key)
	bIV := []byte(iv)
	bPlaintext := PKCS5Padding([]byte(plaintext), blockSize, len(plaintext))
	block, err := aes.NewCipher(bKey)
	if err != nil {
		panic(err)
	}
	ciphertext := make([]byte, len(bPlaintext))
	mode := cipher.NewCBCEncrypter(block, bIV)
	mode.CryptBlocks(ciphertext, bPlaintext)
	return hex.EncodeToString(ciphertext)
}

func Ase256Decode(cipherText string, encKey string, iv string) (decryptedString string) {
	bKey := []byte(encKey)
	bIV := []byte(iv)
	cipherTextDecoded, err := hex.DecodeString(cipherText)
	if err != nil {
		panic(err)
	}

	block, err := aes.NewCipher(bKey)
	if err != nil {
		panic(err)
	}

	mode := cipher.NewCBCDecrypter(block, bIV)
	mode.CryptBlocks([]byte(cipherTextDecoded), []byte(cipherTextDecoded))
	return string(cipherTextDecoded)
}

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