Lots of improvements for package:cryptography.

A short summary of the changes:
 * Better test coverage helped to identify bugs.
 * Some small API changes that are unlikely to affect developers.
   For example, hash sinks now have `outputBytes` and length properties.
 * The documentation was improved.

Author: terrier989

cryptography/CHANGELOG.md

@@ -1,3 +1,12 @@
+## 2.4.0
+* Fixes many issues found by adding more tests. Also improves documentation.
+* Improves performance of SHA256, HMAC, and PBKDF2 by cutting unnecessary state allocations and
+  futures.
+* Some small API refactoring and new class members that don't really affect the publicly visible
+  API. We plan to address most API design issues (some discussed in the issue tracker) in the next
+  major version (3.x).
+* Adds support for seck256k1 key type ([#135](https://github.com/dint-dev/cryptography/pull/135)).
+
 ## 2.3.0
   * Fixes some small issues.
   * Improves documentation.

cryptography/README.md

@@ -13,6 +13,10 @@
 // limitations under the License.
 
 /// @nodoc
+@Deprecated(
+  'This library will be removed in a future major version.'
+  ' You can find `BrowserCryptography` class in "package:cryptography/cryptography.dart".',
+)
 library cryptography.browser;
 
 export 'src/browser/browser_cryptography_when_not_browser.dart'

cryptography/lib/browser.dart

@@ -23,13 +23,16 @@ export 'src/dart/aes_cbc.dart';
 export 'src/dart/aes_ctr.dart';
 export 'src/dart/aes_gcm.dart';
 export 'src/dart/argon2.dart';
-export 'src/dart/base_classes.dart';
 export 'src/dart/blake2b.dart';
 export 'src/dart/blake2s.dart';
 export 'src/dart/chacha20.dart';
-export 'src/dart/chacha20_poly1305_aead.dart';
-export 'src/dart/cipher_base_classes.dart';
+export 'src/dart/chacha20_poly1305_aead_mac_algorithm.dart';
 export 'src/dart/cryptography.dart';
+export 'src/dart/dart_cipher.dart';
+export 'src/dart/dart_hash_algorithm.dart';
+export 'src/dart/dart_key_exchange_algorithm.dart';
+export 'src/dart/dart_mac_algorithm.dart';
+export 'src/dart/dart_signature_algorithm.dart';
 export 'src/dart/ecdh.dart';
 export 'src/dart/ecdsa.dart';
 export 'src/dart/ed25519.dart';
@@ -40,6 +43,8 @@ export 'src/dart/pbkdf2.dart';
 export 'src/dart/poly1305.dart';
 export 'src/dart/rsa_pss.dart';
 export 'src/dart/rsa_ssa_pkcs1v15.dart';
-export 'src/dart/sha1_sha2.dart';
+export 'src/dart/sha1.dart';
+export 'src/dart/sha256.dart';
+export 'src/dart/sha512.dart';
 export 'src/dart/x25519.dart';
 export 'src/dart/xchacha20.dart';

cryptography/lib/dart.dart

@@ -34,7 +34,7 @@ class BrowserHkdf extends Hkdf {
       : super.constructor();
 
   @override
-  Future<SecretKey> deriveKey({
+  Future<SecretKeyData> deriveKey({
     required SecretKey secretKey,
     List<int> nonce = const <int>[],
     List<int> info = const <int>[],
@@ -50,7 +50,7 @@ class BrowserHkdf extends Hkdf {
       jsCryptoKey,
       8 * outputLength,
     );
-    return SecretKey(Uint8List.view(byteBuffer));
+    return SecretKeyData(Uint8List.view(byteBuffer));
   }
 
   Future<web_crypto.CryptoKey> _jsCryptoKey(SecretKey secretKey) async {

cryptography/lib/src/browser/hkdf.dart

@@ -32,6 +32,7 @@ import 'hash.dart';
 class BrowserRsaPss extends RsaPss {
   static const _webCryptoAlgorithm = 'RSA-PSS';
 
+  @override
   final int nonceLengthInBytes;
 
   @override