Encrypt data with AES-256

aes-encryption.go

package encryption

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"errors"
	"fmt"
	"io"
)

// Encrypt encrypts the data using the 256-bit key.
func Encrypt(key, data []byte) ([]byte, error) {
	if len(key) != 32 {
		return nil, errors.New("key must be 32 bytes long")
	}

	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, fmt.Errorf("failed to create AES cipher: %v", err)
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, fmt.Errorf("failed to create GCM: %v", err)
	}

	nonce := make([]byte, gcm.NonceSize())

	_, err = io.ReadFull(rand.Reader, nonce)
	if err != nil {
		return nil, fmt.Errorf("failed to read into nonce: %v", err)
	}

	res := gcm.Seal(nonce, nonce, data, nil)

	return res, nil
}

// Decrypt decrypts the data using the 256-bit key.
func Decrypt(key, data []byte) ([]byte, error) {
	if len(key) != 32 {
		return nil, errors.New("key must be 32 bytes long")
	}

	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, fmt.Errorf("failed to create AES cipher: %v", err)
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, fmt.Errorf("failed to create GCM: %v", err)
	}

	nonceSize := gcm.NonceSize()
	nonce, ciphertext := data[:nonceSize], data[nonceSize:]

	res, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to decrypt: %v", err)
	}

	return res, nil
}