Demo of Data Encrypt/Decrypt with AES 256 Key

aes.key

jHa1bVPQeck+3AsZJa9exEBcI9Pe40XvNSMsezaRr2c=

encrypt.go

package main

import (
    "crypto/aes"
    "crypto/cipher"
    "crypto/rand"
    "encoding/base64"
    "errors"
    "fmt"
    "io"
    "log"
    "io/ioutil"
)

var key []byte

func init() {
    content, err := ioutil.ReadFile("./aes.key")
    if err != nil {
        log.Fatalln("Could not read key file (aes.key)")
    }
    key, err = base64.StdEncoding.DecodeString(string(content))
    if err != nil {
        log.Fatalln("Could not decode base64 key from file (aes.key)")
    }
}

func main() {
    plaintext := []byte("some really really really long plaintext")
    fmt.Printf("%s\n", plaintext)
    ciphertext, err := encrypt(key, plaintext)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("%0x\n", ciphertext)
    result, err := decrypt(key, ciphertext)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("%s\n", result)
}


func encrypt(key, text []byte) ([]byte, error) {
    block, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
    b := base64.StdEncoding.EncodeToString(text)
    ciphertext := make([]byte, aes.BlockSize+len(b))
    iv := ciphertext[:aes.BlockSize]
    if _, err := io.ReadFull(rand.Reader, iv); err != nil {
        return nil, err
    }
    cfb := cipher.NewCFBEncrypter(block, iv)
    cfb.XORKeyStream(ciphertext[aes.BlockSize:], []byte(b))
    return ciphertext, nil
}

func decrypt(key, text []byte) ([]byte, error) {
    block, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
    if len(text) < aes.BlockSize {
        return nil, errors.New("ciphertext too short")
    }
    iv := text[:aes.BlockSize]
    text = text[aes.BlockSize:]
    cfb := cipher.NewCFBDecrypter(block, iv)
    cfb.XORKeyStream(text, text)
    data, err := base64.StdEncoding.DecodeString(string(text))
    if err != nil {
        return nil, err
    }
    return data, nil
}

generate_aes_key.go

package main

import (
	"crypto/rand"
	"fmt"
	b64 "encoding/base64"
	"encoding/hex"
	"io/ioutil"
)

func main() {
    key := make([]byte, 32)

    _, err := rand.Read(key)
    if err != nil {
        // handle error here
    }


    fmt.Println("=================")
    fmt.Println(key)
    fmt.Println("=================")
    sEnc := b64.StdEncoding.EncodeToString(key)
    fmt.Println(sEnc)
	fmt.Println("=================")
	sEnc2 := hex.EncodeToString(key)
	fmt.Println(sEnc2)
	fmt.Println("=================")
    sDec, _ := b64.StdEncoding.DecodeString(sEnc)
    fmt.Println(sDec)
    fmt.Println("=================")
	sDec2, _ := hex.DecodeString(sEnc2)
	fmt.Println(sDec2)

	d1 := []byte(sEnc)
	_ = ioutil.WriteFile("./aes.key", d1, 0644)

	content, err := ioutil.ReadFile("./aes.key")
	if err != nil {
		//Do something
	}
	fmt.Println(string(content))
	fmt.Println("=================")
	sDec, _ = b64.StdEncoding.DecodeString(string(content))
	fmt.Println(sDec)
}