encryption.go

package configHandler

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/json"
	"io"
)

func checkIfTextIsEncrypted(text []byte) bool {
	return !json.Valid(text)
}

func encrypt(key []byte, plaintext []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, err
	}

	nonce := make([]byte, gcm.NonceSize())
	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
		return nil, err
	}

	ciphertext := gcm.Seal(nonce, nonce, plaintext, nil)
	return ciphertext, err
}

func decrypt(key []byte, ciphertext []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, err
	}

	nonce := ciphertext[:gcm.NonceSize()]
	ciphertext = ciphertext[gcm.NonceSize():]
	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return nil, err
	}
	return plaintext, err
}

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

	_, err := rand.Read(key)
	if err != nil {
		return nil, err
	}
	return key, err
}

func prepareKey(key []byte, salt string) []byte {
	var keyString = string(key)
	if len(key) > len(salt) {
		key = []byte(salt + keyString[len(salt):])
	}
	return key
}