golang-enc-dec.go

package main

import (
	"crypto/aes"
	"crypto/cipher"
	"encoding/hex"
	"fmt"
)

func main() {
	main2()
}

func main3() {
	plainText := []byte("This is 16 bytes")

	key := []byte("passw0rdpassw0rdpassw0rdpassw0rd")

	block, err := aes.NewCipher(key)
	if err != nil {
		fmt.Printf("err: %s\n", err)
		return
	}

	// Encrypt
	encTxtBytes := make([]byte, len(plainText))
	block.Encrypt(encTxtBytes, plainText)
	//fmt.Printf("Cipher text: %x\n", cipherText)
	fmt.Println(encTxtBytes)
	fmt.Println(hex.EncodeToString(encTxtBytes))
	fmt.Println(string(encTxtBytes))

	encTxtBytes, _ = hex.DecodeString("46fa10fded0bc105a2c63365fe56f932")

	// Decrypt
	decryptedText := make([]byte, len(encTxtBytes))
	block.Decrypt(decryptedText, encTxtBytes)
	fmt.Printf("Decrypted text: %s\n", string(decryptedText))
}

func main2() {
	iv := []byte("1234567890abcdef") // initialization vector
	//iv, _ := hex.DecodeString("5a61e625e2036c3c8cbcc2d40b451b0e") // initialization vector
	//hexEnc := enc("someplaintext", "1234567812345678", iv)
	hexEnc := enc("someplaintext123456789", "1234567812345678", iv)
	fmt.Println(hexEnc) //
	dec(hexEnc, "1234567812345678", iv)
	//dec("00000000000000000000000000000000bb1bd0be1850ed8e55bfea196f", "1234567812345678", iv)
}
func dec(hexCipherText string, skey string, iv []byte) {
	bCipherText, _ := hex.DecodeString(hexCipherText)
	plaintext := make([]byte, len(bCipherText)) // ここのバイト配列のサイズは大きくても大丈夫なので、暗号化後の長さを入れている。
	key := []byte(skey)
	fmt.Println(plaintext)

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

	stream := cipher.NewCTR(block, iv)
	stream.XORKeyStream(plaintext, bCipherText[aes.BlockSize:])
	fmt.Println(plaintext)
	fmt.Println(string(plaintext))
}

func enc(src string, skey string, iv []byte) string {
	srcTxtBytes := []byte(src)
	key := []byte(skey)

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

	// init
	encTxtBytes := make([]byte, aes.BlockSize+len(srcTxtBytes))

	stream := cipher.NewCTR(block, iv)
	stream.XORKeyStream(encTxtBytes[aes.BlockSize:], srcTxtBytes)
	fmt.Println(encTxtBytes)
	fmt.Println(hex.EncodeToString(encTxtBytes))
	fmt.Println(string(encTxtBytes))
	return hex.EncodeToString(encTxtBytes)
}