diff --git a/main.go b/main.go
index b8d04e2..5ff9cf3 100644
--- a/main.go
+++ b/main.go
@@ -5,6 +5,7 @@ import (
 	"crypto/cipher"
 	"crypto/rand"
 	"errors"
+	"fmt"
 	"io"
 	mrand "math/rand"
 	"time"
@@ -15,7 +16,7 @@ const (
 	allowedRunes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
 )
 
-// RandomKey returns a randomly generated 32 bytes long hex encoded key.
+// RandomKey returns a randomly generated 32 bytes long key.
 func RandomKey() (key []byte) {
 	mrand.Seed(time.Now().UnixNano())
 
@@ -29,7 +30,11 @@ func RandomKey() (key []byte) {
 }
 
 // Encrypt encrypts plaintext with key and returns resulting bytes.
-func Encrypt(plaintext []byte, key []byte) ([]byte, error) {
+func Encrypt(plaintext, key []byte) ([]byte, error) {
+	if len(key) != keySize {
+		return nil, fmt.Errorf("key size invalid: %d, must be %d\n", len(key), keySize)
+	}
+
 	c, err := aes.NewCipher(key)
 	if err != nil {
 		return nil, err
@@ -49,7 +54,7 @@ func Encrypt(plaintext []byte, key []byte) ([]byte, error) {
 }
 
 // Decrypt decrypts ciphertext with key and returns resulting bytes.
-func Decrypt(ciphertext []byte, key []byte) ([]byte, error) {
+func Decrypt(ciphertext, key []byte) ([]byte, error) {
 	c, err := aes.NewCipher(key)
 	if err != nil {
 		return nil, err
@@ -66,5 +71,6 @@ func Decrypt(ciphertext []byte, key []byte) ([]byte, error) {
 	}
 
 	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+
 	return gcm.Open(nil, nonce, ciphertext, nil)
 }