fix: update code to pass all tests

packages/native_crypto/example/lib/pages/cipher_page.dart

@@ -3,7 +3,7 @@
 // -----
 // File: cipher_page.dart
 // Created Date: 28/12/2021 13:33:15
-// Last Modified: 26/05/2022 20:39:37
+// Last Modified: 26/05/2022 21:07:54
 // -----
 // Copyright (c) 2021
 
@@ -26,7 +26,8 @@ class CipherPage extends ConsumerWidget {
   final Output encryptionStatus = Output();
   final Output decryptionStatus = Output();
 
-  final TextEditingController _plainTextController = TextEditingController()..text = 'PlainText';
+  final TextEditingController _plainTextController = TextEditingController()
+    ..text = 'PlainText';
   CipherTextWrapper? cipherText;
 
   Future<void> _encrypt(WidgetRef ref, Cipher cipher) async {
@@ -58,9 +59,10 @@ class CipherPage extends ConsumerWidget {
       // Recreate cipher text with altered data
       cipherText = CipherTextWrapper.fromBytes(
         _altered,
-        12,
-        _altered.length - 28,
-        16,
+        ivLength: AESMode.gcm.ivLength,
+        messageLength:
+            _altered.length - (AESMode.gcm.ivLength + AESMode.gcm.tagLength),
+        tagLength: AESMode.gcm.tagLength,
       );
       encryptionStatus.print('String successfully encrypted:\n');
 

packages/native_crypto/example/lib/pages/kdf_page.dart

@@ -3,7 +3,7 @@
 // -----
 // File: kdf_page.dart
 // Created Date: 28/12/2021 13:40:34
-// Last Modified: 26/05/2022 20:30:31
+// Last Modified: 26/05/2022 21:09:47
 // -----
 // Copyright (c) 2021
 
@@ -26,8 +26,10 @@ class KdfPage extends ConsumerWidget {
   final Output pbkdf2Status = Output();
   final Output hashStatus = Output(large: true);
 
-  final TextEditingController _pwdTextController = TextEditingController()..text = 'Password';
-  final TextEditingController _messageTextController = TextEditingController()..text = 'Message';
+  final TextEditingController _pwdTextController = TextEditingController()
+    ..text = 'Password';
+  final TextEditingController _messageTextController = TextEditingController()
+    ..text = 'Message';
 
   Future<void> _generate(WidgetRef ref) async {
     Session state = ref.read(sessionProvider.state).state;
@@ -50,7 +52,11 @@ class KdfPage extends ConsumerWidget {
     if (password.isEmpty) {
       pbkdf2Status.print('Password is empty');
     } else {
-      Pbkdf2 _pbkdf2 = Pbkdf2(32, 1000, algorithm: HashAlgorithm.sha512);
+      Pbkdf2 _pbkdf2 = Pbkdf2(
+        keyBytesCount: 32,
+        iterations: 1000,
+        algorithm: HashAlgorithm.sha512,
+      );
       SecretKey sk = await _pbkdf2.derive(password: password, salt: 'salt');
       state.setKey(sk);
       pbkdf2Status.print('Key successfully derived.');

packages/native_crypto/lib/src/ciphers/aes/aes.dart

@@ -3,7 +3,7 @@
 // -----
 // File: aes.dart
 // Created Date: 16/12/2021 16:28:00
-// Last Modified: 26/05/2022 19:43:22
+// Last Modified: 26/05/2022 21:07:01
 // -----
 // Copyright (c) 2022
 
@@ -21,6 +21,10 @@ import 'package:native_crypto/src/utils/cipher_algorithm.dart';
 import 'package:native_crypto/src/utils/extensions.dart';
 import 'package:native_crypto_platform_interface/native_crypto_platform_interface.dart';
 
+export 'aes_key_size.dart';
+export 'aes_mode.dart';
+export 'aes_padding.dart';
+
 /// An AES cipher.
 ///
 /// [AES] is a [Cipher] that can be used to encrypt or decrypt data.
@@ -94,11 +98,11 @@ class AES implements Cipher {
       );
     } else {
       return CipherText.fromBytes(
-        12,
-        encrypted.length - 28,
-        16,
-        CipherAlgorithm.aes,
         encrypted,
+        ivLength: 12,
+        messageLength: encrypted.length - 28,
+        tagLength: 16,
+        cipherAlgorithm: CipherAlgorithm.aes,
       );
     }
   }

packages/native_crypto/lib/src/ciphers/aes/aes_mode.dart

@@ -3,7 +3,7 @@
 // -----
 // File: aes_mode.dart
 // Created Date: 23/05/2022 22:09:16
-// Last Modified: 26/05/2022 18:41:31
+// Last Modified: 26/05/2022 21:03:26
 // -----
 // Copyright (c) 2022
 
@@ -11,10 +11,20 @@ import 'package:native_crypto/src/ciphers/aes/aes_padding.dart';
 
 /// Defines the AES modes of operation.
 enum AESMode {
-  gcm([AESPadding.none]);
+  gcm([AESPadding.none], 12, 16);
 
   /// Returns the list of supported [AESPadding] for this [AESMode].
   final List<AESPadding> supportedPaddings;
 
-  const AESMode(this.supportedPaddings);
+  /// Returns the default IV length for this [AESMode].
+  final int ivLength;
+
+  /// Returns the default tag length for this [AESMode].
+  final int tagLength;
+
+  const AESMode(
+    this.supportedPaddings, [
+    this.ivLength = 16,
+    this.tagLength = 0,
+  ]);
 }

packages/native_crypto/lib/src/core/cipher_text.dart

@@ -3,7 +3,7 @@
 // -----
 // File: cipher_text.dart
 // Created Date: 16/12/2021 16:59:53
-// Last Modified: 26/05/2022 19:43:57
+// Last Modified: 26/05/2022 22:20:40
 // -----
 // Copyright (c) 2021
 
@@ -27,7 +27,7 @@ import 'package:native_crypto_platform_interface/native_crypto_platform_interfac
 /// - IV's length is [CipherText.ivLength] bytes.
 /// - MESSAGE's length is [CipherText.messageLength] bytes.
 /// - TAG's length is [CipherText.tagLength] bytes.
-/// 
+///
 /// Check [CipherTextWrapper] for more information.
 class CipherText extends ByteArray {
   final int _ivLength;
@@ -45,16 +45,33 @@ class CipherText extends ByteArray {
   );
 
   factory CipherText.fromBytes(
-    int ivLength,
-    int messageLength,
-    int tagLength,
+    Uint8List bytes, {
+    required int ivLength,
+    required int messageLength,
+    required int tagLength,
     CipherAlgorithm? cipherAlgorithm,
-    Uint8List bytes,
-  ) {
+  }) {
+    if (ivLength.isNegative ||
+        messageLength.isNegative ||
+        tagLength.isNegative) {
+      throw NativeCryptoException(
+        message: 'Invalid length! Must be positive.',
+        code: NativeCryptoExceptionCode.invalid_argument.code,
+      );
+    }
+
+    if (bytes.isEmpty) {
+      throw NativeCryptoException(
+        message: 'Passed data is empty!',
+        code: NativeCryptoExceptionCode.invalid_argument.code,
+      );
+    }
+
     if (bytes.length != ivLength + messageLength + tagLength) {
       throw NativeCryptoException(
         message: 'Invalid cipher text length! '
-            'Expected: ${ivLength + messageLength + tagLength} bytes',
+            'Expected: ${ivLength + messageLength + tagLength} bytes '
+            'got: ${bytes.length} bytes.',
         code: NativeCryptoExceptionCode.invalid_argument.code,
       );
     }

packages/native_crypto/lib/src/core/cipher_text_wrapper.dart

@@ -3,7 +3,7 @@
 // -----
 // File: cipher_text_wrapper.dart
 // Created Date: 26/05/2022 14:27:32
-// Last Modified: 26/05/2022 20:32:38
+// Last Modified: 26/05/2022 22:11:42
 // -----
 // Copyright (c) 2022
 
@@ -49,10 +49,10 @@ class CipherTextWrapper {
   /// [NativeCryptoExceptionCode.invalid_argument] if the [Uint8List] is
   /// not a valid [CipherText] or a [List] of [CipherText].
   factory CipherTextWrapper.fromBytes(
-    Uint8List bytes,
-    int ivLength,
-    int messageLength,
-    int tagLength, {
+    Uint8List bytes, {
+    required int ivLength,
+    required int messageLength,
+    required int tagLength,
     CipherAlgorithm? cipherAlgorithm,
     int? chunkSize,
   }) {
@@ -62,11 +62,11 @@ class CipherTextWrapper {
     if (bytes.length <= chunkSize) {
       return CipherTextWrapper.single(
         CipherText.fromBytes(
-          ivLength,
-          messageLength,
-          tagLength,
-          cipherAlgorithm,
           bytes,
+          ivLength: ivLength,
+          messageLength: messageLength,
+          tagLength: tagLength,
+          cipherAlgorithm: cipherAlgorithm,
         ),
       );
     } else {
@@ -75,11 +75,11 @@ class CipherTextWrapper {
         final chunk = bytes.sublist(i, i + chunkSize);
         cipherTexts.add(
           CipherText.fromBytes(
-            ivLength,
-            messageLength,
-            tagLength,
-            cipherAlgorithm,
             chunk,
+            ivLength: ivLength,
+            messageLength: messageLength,
+            tagLength: tagLength,
+            cipherAlgorithm: cipherAlgorithm,
           ),
         );
       }
@@ -128,7 +128,7 @@ class CipherTextWrapper {
     if (isSingle) {
       return single.bytes;
     } else {
-      return list.map((cipherText) => cipherText.bytes).toList().sum();
+      return list.map((cipherText) => cipherText.bytes).toList().combine();
     }
   }
 

packages/native_crypto/lib/src/interfaces/cipher.dart

@@ -3,7 +3,7 @@
 // -----
 // File: cipher.dart
 // Created Date: 16/12/2021 16:28:00
-// Last Modified: 26/05/2022 17:38:26
+// Last Modified: 26/05/2022 21:21:07
 // -----
 // Copyright (c) 2021
 
@@ -20,7 +20,11 @@ import 'package:native_crypto/src/utils/cipher_algorithm.dart';
 /// 
 /// This interface is implemented by all the ciphers in NativeCrypto.
 abstract class Cipher {
-  static int _bytesCountPerChunk = 33554432;
+  static const int _bytesCountPerChunkDefault = 33554432;
+  static int _bytesCountPerChunk = _bytesCountPerChunkDefault;
+
+  /// Returns the default number of bytes per chunk.
+  static int get defaultBytesCountPerChunk => _bytesCountPerChunkDefault;
 
   /// Returns the size of a chunk of data 
   /// that can be processed by the [Cipher].

packages/native_crypto/lib/src/kdf/pbkdf2.dart

@@ -3,7 +3,7 @@
 // -----
 // File: pbkdf2.dart
 // Created Date: 17/12/2021 14:50:42
-// Last Modified: 26/05/2022 18:51:59
+// Last Modified: 26/05/2022 23:19:46
 // -----
 // Copyright (c) 2021
 
@@ -29,31 +29,64 @@ class Pbkdf2 extends KeyDerivation {
   @override
   KdfAlgorithm get algorithm => KdfAlgorithm.pbkdf2;
 
-  Pbkdf2(
-    int keyBytesCount,
-    int iterations, {
+  Pbkdf2({
+    required int keyBytesCount,
+    required int iterations,
     HashAlgorithm algorithm = HashAlgorithm.sha256,
   })  : _keyBytesCount = keyBytesCount,
         _iterations = iterations,
-        _hash = algorithm;
-
-  @override
-  Future<SecretKey> derive({String? password, String? salt}) async {
-    if (password == null || salt == null) {
+        _hash = algorithm {
+    if (keyBytesCount < 0) {
       throw NativeCryptoException(
-        message: 'Password and salt cannot be null. '
-            'Here is the password: $password, here is the salt: $salt',
+        message: 'keyBytesCount must be positive.',
         code: NativeCryptoExceptionCode.invalid_argument.code,
       );
     }
 
-    final Uint8List? derivation = await platform.pbkdf2(
-      password,
-      salt,
-      _keyBytesCount,
-      _iterations,
-      _hash.name,
-    );
+    if (iterations <= 0) {
+      throw NativeCryptoException(
+        message: 'iterations must be strictly positive.',
+        code: NativeCryptoExceptionCode.invalid_argument.code,
+      );
+    }
+  }
+
+  @override
+  Future<SecretKey> derive({String? password, String? salt}) async {
+    Uint8List? derivation;
+
+    if (_keyBytesCount == 0) {
+      return SecretKey(Uint8List(0));
+    }
+    if (password.isNull) {
+      throw NativeCryptoException(
+        message: 'Password cannot be null.',
+        code: NativeCryptoExceptionCode.invalid_argument.code,
+      );
+    }
+
+    if (salt.isNull) {
+      throw NativeCryptoException(
+        message: 'Salt cannot be null.',
+        code: NativeCryptoExceptionCode.invalid_argument.code,
+      );
+    }
+
+    try {
+      derivation = await platform.pbkdf2(
+        password!,
+        salt!,
+        _keyBytesCount,
+        _iterations,
+        _hash.name,
+      );
+    } catch (e, s) {
+      throw NativeCryptoException(
+        message: '$e',
+        code: NativeCryptoExceptionCode.platform_throws.code,
+        stackTrace: s,
+      );
+    }
 
     if (derivation.isNull) {
       throw NativeCryptoException(

packages/native_crypto/lib/src/keys/secret_key.dart

@@ -3,7 +3,7 @@
 // -----
 // File: secret_key.dart
 // Created Date: 28/12/2021 13:36:54
-// Last Modified: 26/05/2022 19:26:35
+// Last Modified: 26/05/2022 23:13:10
 // -----
 // Copyright (c) 2021
 
@@ -28,6 +28,10 @@ class SecretKey extends BaseKey {
 
   static Future<SecretKey> fromSecureRandom(int bitsCount) async {
     Uint8List? key;
+    if (bitsCount == 0) {
+      return SecretKey(Uint8List(0));
+    }
+
     try {
       key = await platform.generateSecretKey(bitsCount);
     } catch (e, s) {

packages/native_crypto/lib/src/utils/extensions.dart

@@ -3,7 +3,7 @@
 // -----
 // File: extensions.dart
 // Created Date: 26/05/2022 12:12:48
-// Last Modified: 26/05/2022 18:52:48
+// Last Modified: 26/05/2022 22:15:33
 // -----
 // Copyright (c) 2022
 
@@ -19,7 +19,7 @@ extension ObjectX on Object? {
 
   /// Returns `true` if the object is **not** `null`.
   bool get isNotNull => this != null;
-  
+
   /// Prints the object to the console.
   void log() => developer.log(toString());
 }
@@ -30,14 +30,10 @@ extension ListIntX on List<int> {
 }
 
 extension ListUint8ListX on List<Uint8List> {
-  
   /// Reduce a [List] of [Uint8List] to a [Uint8List].
-  Uint8List sum() {
-    for (var i = 1; i < length; i++) {
-      first.addAll(this[i]);
-      removeAt(i);
-    }
-    return first;
+  Uint8List combine() {
+    if (isEmpty) return Uint8List(0);
+    return reduce((value, element) => value.plus(element));
   }
 }
 
@@ -90,6 +86,5 @@ extension Uint8ListX on Uint8List {
   }
 
   /// Returns a concatenation of this with the other [Uint8List].
-  Uint8List operator +(final Uint8List other) =>
-      [...this, ...other].toTypedList();
+  Uint8List plus(final Uint8List other) => [...this, ...other].toTypedList();
 }

packages/native_crypto/lib/src/utils/hash_algorithm.dart

@@ -3,23 +3,48 @@
 // -----
 // File: hash_algorithm.dart
 // Created Date: 23/05/2022 22:01:59
-// Last Modified: 26/05/2022 18:53:38
+// Last Modified: 26/05/2022 22:59:04
 // -----
 // Copyright (c) 2022
 
 import 'dart:typed_data';
 
 import 'package:native_crypto/src/platform.dart';
+import 'package:native_crypto/src/utils/extensions.dart';
+import 'package:native_crypto_platform_interface/native_crypto_platform_interface.dart';
 
 /// Defines the hash algorithms.
 enum HashAlgorithm {
   sha256,
   sha384,
   sha512;
-  
+
   /// Digest the [data] using this [HashAlgorithm].
   Future<Uint8List> digest(Uint8List data) async {
-    final Uint8List hash = (await platform.digest(data, name)) ?? Uint8List(0);
+    Uint8List? hash;
+    try {
+      hash = await platform.digest(data, name);
+    } catch (e, s) {
+      throw NativeCryptoException(
+        message: '$e',
+        code: NativeCryptoExceptionCode.platform_throws.code,
+        stackTrace: s,
+      );
+    }
+
+    if (hash.isNull) {
+      throw NativeCryptoException(
+        message: 'Failed to digest data! Platform returned null.',
+        code: NativeCryptoExceptionCode.platform_returned_null.code,
+      );
+    }
+
+    if (hash!.isEmpty) {
+      throw NativeCryptoException(
+        message: 'Failed to digest data! Platform returned no data.',
+        code: NativeCryptoExceptionCode.platform_returned_empty_data.code,
+      );
+    }
 
     return hash;
   }