eugenp · eric-martin · Mar 20, 2025 · May 16, 2024 · May 23, 2024 · May 24, 2024
diff --git a/core-java-modules/core-java-security-algorithms/src/main/java/com/baeldung/aes/AESUtil.java b/core-java-modules/core-java-security-algorithms/src/main/java/com/baeldung/aes/AESUtil.java
@@ -8,6 +8,7 @@
 import javax.crypto.KeyGenerator;
 import javax.crypto.SecretKeyFactory;
 import javax.crypto.SealedObject;
+import javax.crypto.spec.GCMParameterSpec;
 import javax.crypto.spec.IvParameterSpec;
 import javax.crypto.spec.PBEKeySpec;
 import javax.crypto.spec.SecretKeySpec;
@@ -26,7 +27,7 @@
 
 public class AESUtil {
 
-    public static String encrypt(String algorithm, String input, SecretKey key, IvParameterSpec iv)
+    public static String encrypt(String algorithm, String input, SecretKey key, GCMParameterSpec iv)
         throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
         InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
         Cipher cipher = Cipher.getInstance(algorithm);
@@ -36,7 +37,7 @@ public static String encrypt(String algorithm, String input, SecretKey key, IvPa
             .encodeToString(cipherText);
     }
 
-    public static String decrypt(String algorithm, String cipherText, SecretKey key, IvParameterSpec iv)
+    public static String decrypt(String algorithm, String cipherText, SecretKey key, GCMParameterSpec iv)
         throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
         InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
         Cipher cipher = Cipher.getInstance(algorithm);
@@ -62,13 +63,13 @@ public static SecretKey getKeyFromPassword(String password, String salt)
         return secret;
     }
 
-    public static IvParameterSpec generateIv() {
-        byte[] iv = new byte[16];
+    public static GCMParameterSpec generateIv() {
+        byte[] iv = new byte[12];
         new SecureRandom().nextBytes(iv);
-        return new IvParameterSpec(iv);
+        return new GCMParameterSpec(128, iv);
     }
 
-    public static void encryptFile(String algorithm, SecretKey key, IvParameterSpec iv,
+    public static void encryptFile(String algorithm, SecretKey key, GCMParameterSpec iv,
         File inputFile, File outputFile) throws IOException, NoSuchPaddingException,
         NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException,
         BadPaddingException, IllegalBlockSizeException {
@@ -92,7 +93,7 @@ public static void encryptFile(String algorithm, SecretKey key, IvParameterSpec
         outputStream.close();
     }
 
-    public static void decryptFile(String algorithm, SecretKey key, IvParameterSpec iv,
+    public static void decryptFile(String algorithm, SecretKey key, GCMParameterSpec iv,
         File encryptedFile, File decryptedFile) throws IOException, NoSuchPaddingException,
         NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException,
         BadPaddingException, IllegalBlockSizeException {
@@ -117,7 +118,7 @@ public static void decryptFile(String algorithm, SecretKey key, IvParameterSpec
     }
 
     public static SealedObject encryptObject(String algorithm, Serializable object, SecretKey key,
-        IvParameterSpec iv) throws NoSuchPaddingException, NoSuchAlgorithmException,
+        GCMParameterSpec iv) throws NoSuchPaddingException, NoSuchAlgorithmException,
         InvalidAlgorithmParameterException, InvalidKeyException, IOException, IllegalBlockSizeException {
         Cipher cipher = Cipher.getInstance(algorithm);
         cipher.init(Cipher.ENCRYPT_MODE, key, iv);
@@ -126,7 +127,7 @@ public static SealedObject encryptObject(String algorithm, Serializable object,
     }
 
     public static Serializable decryptObject(String algorithm, SealedObject sealedObject, SecretKey key,
-        IvParameterSpec iv) throws NoSuchPaddingException, NoSuchAlgorithmException,
+        GCMParameterSpec iv) throws NoSuchPaddingException, NoSuchAlgorithmException,
         InvalidAlgorithmParameterException, InvalidKeyException, ClassNotFoundException,
         BadPaddingException, IllegalBlockSizeException, IOException {
         Cipher cipher = Cipher.getInstance(algorithm);
@@ -135,19 +136,19 @@ public static Serializable decryptObject(String algorithm, SealedObject sealedOb
         return unsealObject;
     }
 
-    public static String encryptPasswordBased(String plainText, SecretKey key, IvParameterSpec iv)
+    public static String encryptPasswordBased(String plainText, SecretKey key, GCMParameterSpec iv)
         throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
         InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
-        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
         cipher.init(Cipher.ENCRYPT_MODE, key, iv);
         return Base64.getEncoder()
             .encodeToString(cipher.doFinal(plainText.getBytes()));
     }
 
-    public static String decryptPasswordBased(String cipherText, SecretKey key, IvParameterSpec iv)
+    public static String decryptPasswordBased(String cipherText, SecretKey key, GCMParameterSpec iv)
         throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
         InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
-        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
+        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
         cipher.init(Cipher.DECRYPT_MODE, key, iv);
         return new String(cipher.doFinal(Base64.getDecoder()
             .decode(cipherText)));

diff --git a/...modules/core-java-security-algorithms/src/test/java/com/baeldung/aes/AESUtilUnitTest.java b/...modules/core-java-security-algorithms/src/test/java/com/baeldung/aes/AESUtilUnitTest.java
@@ -6,6 +6,7 @@
 
 import javax.crypto.SealedObject;
 import javax.crypto.SecretKey;
+import javax.crypto.spec.GCMParameterSpec;
 import javax.crypto.spec.IvParameterSpec;
 import javax.crypto.BadPaddingException;
 import javax.crypto.IllegalBlockSizeException;
@@ -27,12 +28,12 @@ void givenString_whenEncrypt_thenSuccess()
         // given
         String input = "baeldung";
         SecretKey key = AESUtil.generateKey(128);
-        IvParameterSpec ivParameterSpec = AESUtil.generateIv();
-        String algorithm = "AES/CBC/PKCS5Padding";
+        GCMParameterSpec gcmParameterSpec = AESUtil.generateIv();
+        String algorithm = "AES/GCM/NoPadding";
 
         // when
-        String cipherText = AESUtil.encrypt(algorithm, input, key, ivParameterSpec);
-        String plainText = AESUtil.decrypt(algorithm, cipherText, key, ivParameterSpec);
+        String cipherText = AESUtil.encrypt(algorithm, input, key, gcmParameterSpec);
+        String plainText = AESUtil.decrypt(algorithm, cipherText, key, gcmParameterSpec);
 
         // then
         Assertions.assertEquals(input, plainText);
@@ -44,16 +45,16 @@ void givenFile_whenEncrypt_thenSuccess()
         BadPaddingException, InvalidAlgorithmParameterException, NoSuchPaddingException {
         // given
         SecretKey key = AESUtil.generateKey(128);
-        String algorithm = "AES/CBC/PKCS5Padding";
-        IvParameterSpec ivParameterSpec = AESUtil.generateIv();
+        String algorithm = "AES/GCM/NoPadding";
+        GCMParameterSpec gcmParameterSpec = AESUtil.generateIv();
         File inputFile = Paths.get("src/test/resources/baeldung.txt")
             .toFile();
         File encryptedFile = new File("baeldung.encrypted");
         File decryptedFile = new File("document.decrypted");
 
         // when
-        AESUtil.encryptFile(algorithm, key, ivParameterSpec, inputFile, encryptedFile);
-        AESUtil.decryptFile(algorithm, key, ivParameterSpec, encryptedFile, decryptedFile);
+        AESUtil.encryptFile(algorithm, key, gcmParameterSpec, inputFile, encryptedFile);
+        AESUtil.decryptFile(algorithm, key, gcmParameterSpec, encryptedFile, decryptedFile);
 
         // then
         assertThat(inputFile).hasSameTextualContentAs(decryptedFile);
@@ -69,12 +70,12 @@ void givenObject_whenEncrypt_thenSuccess()
         // given
         Student student = new Student("Baeldung", 20);
         SecretKey key = AESUtil.generateKey(128);
-        IvParameterSpec ivParameterSpec = AESUtil.generateIv();
-        String algorithm = "AES/CBC/PKCS5Padding";
+        GCMParameterSpec gcmParameterSpec = AESUtil.generateIv();
+        String algorithm = "AES/GCM/NoPadding";
 
         // when
-        SealedObject sealedObject = AESUtil.encryptObject(algorithm, student, key, ivParameterSpec);
-        Student object = (Student) AESUtil.decryptObject(algorithm, sealedObject, key, ivParameterSpec);
+        SealedObject sealedObject = AESUtil.encryptObject(algorithm, student, key, gcmParameterSpec);
+        Student object = (Student) AESUtil.decryptObject(algorithm, sealedObject, key, gcmParameterSpec);
 
         // then
         assertThat(student).isEqualTo(object);
@@ -88,12 +89,12 @@ void givenPassword_whenEncrypt_thenSuccess()
         String plainText = "www.baeldung.com";
         String password = "baeldung";
         String salt = "12345678";
-        IvParameterSpec ivParameterSpec = AESUtil.generateIv();
+        GCMParameterSpec gcmParameterSpec = AESUtil.generateIv();
         SecretKey key = AESUtil.getKeyFromPassword(password, salt);
 
         // when
-        String cipherText = AESUtil.encryptPasswordBased(plainText, key, ivParameterSpec);
-        String decryptedCipherText = AESUtil.decryptPasswordBased(cipherText, key, ivParameterSpec);
+        String cipherText = AESUtil.encryptPasswordBased(plainText, key, gcmParameterSpec);
+        String decryptedCipherText = AESUtil.decryptPasswordBased(cipherText, key, gcmParameterSpec);
 
         // then
         Assertions.assertEquals(plainText, decryptedCipherText);