Encrpyt and decrpyt with a public and private key using RSA

encrpytAndDecrpyt.go

func main() {
	key, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		log.Fatal(err)
	}

	// Generate keyFile to memory
	keyFile := pem.EncodeToMemory(&pem.Block{Type: "RSA PUBLIC KEY", Bytes: x509.MarshalPKCS1PublicKey(&key.PublicKey)})

	// Create a public key from the public keyFile
	pubBlock, _ := pem.Decode(keyFile)
	pub, err := x509.ParsePKCS1PublicKey(pubBlock.Bytes)
	if err != nil {
		log.Fatal(err)
	}

	// toSend is what will be encrypted and decrpyted again
	// The part before the | is the hashed public key
	toSend := fmt.Sprintf("%x|%v", sha256.Sum256(keyFile), "Password for: github.com")

	// This part encrypts the data
	encryptedData, err := rsa.EncryptOAEP(sha256.New(), rand.Reader, pub, []byte(toSend), []byte("PUBLIC KEY HOST"))
	if err != nil {
		log.Fatal(err)
	}

	// Here we decrypt the message again
	outMsg, err := rsa.DecryptOAEP(sha256.New(), rand.Reader, key, encryptedData, []byte("PUBLIC KEY HOST"))
	if err != nil {
		log.Fatal(err)
	}

	// print the output
	fmt.Println(string(outMsg))
}