Migrate from steel_crypt to crypton

SteelCrypt is deprecating asymetric key crypto functions and recommends
using crypton. This also simplifies our code.

lib/ssh/rsa_key_pair.dart

@@ -1,16 +1,11 @@
 import 'dart:async';
 import 'dart:convert';
-import 'dart:math';
-import 'dart:typed_data';
 
 import 'package:isolate/isolate_runner.dart';
 import 'package:meta/meta.dart';
 import 'package:ssh_key/ssh_key.dart' as ssh_key;
-import 'package:steel_crypt/PointyCastleN/key_generators/rsa_key_generator.dart';
-import 'package:steel_crypt/PointyCastleN/pointycastle.dart';
-import 'package:steel_crypt/PointyCastleN/random/fortuna_random.dart';
-import 'package:steel_crypt/steel_crypt.dart';
 
+import 'package:crypton/crypton.dart';
 import 'package:gitjournal/error_reporting.dart';
 import 'package:gitjournal/ssh/binary_length_value.dart';
 import 'package:gitjournal/utils/logger.dart';
@@ -23,8 +18,6 @@ class RsaKeyPair {
     @required String privateKey,
     @required String publicKey,
   }) {
-    var encrypter = RsaCrypt();
-
     publicKey = publicKey.trim();
     try {
       var key = ssh_key.publicKeyDecode(publicKey);
@@ -37,41 +30,43 @@ class RsaKeyPair {
 
     if (publicKey == null) {
       try {
-        this.publicKey = encrypter.parseKeyFromString(publicKey);
+        this.publicKey = RSAPublicKey.fromString(publicKey);
       } catch (e) {
         // Ignore
       }
     }
 
     try {
-      this.privateKey = encrypter.parseKeyFromString(privateKey);
+      this.privateKey = RSAPrivateKey.fromPEM(privateKey);
     } catch (e) {
       // Ignore
     }
   }
 
   RsaKeyPair.generate() {
-    var keyPair = _getRsaKeyPair(_getSecureRandom());
-    publicKey = keyPair.publicKey as RSAPublicKey;
-    privateKey = keyPair.privateKey as RSAPrivateKey;
+    var keyPair = RSAKeypair.fromRandom();
+
+    publicKey = keyPair.publicKey;
+    privateKey = keyPair.privateKey;
   }
 
   // Tries to encrypt and decrypt
   bool isValid() {
-    var encrypter = RsaCrypt();
     var orig = 'word';
-    var enc = encrypter.encrypt(orig, publicKey);
-    var dec = encrypter.decrypt(enc, privateKey);
+    var enc = publicKey.encrypt(orig);
+    var dec = privateKey.decrypt(enc);
 
     return orig == dec;
   }
 
   // OpenSSH Public Key (single-line format)
   String publicKeyString({String comment = ""}) {
+    var pk = publicKey.asPointyCastle;
+
     var data = BinaryLengthValue.encode([
       BinaryLengthValue.fromString("ssh-rsa"),
-      BinaryLengthValue.fromBigInt(publicKey.exponent),
-      BinaryLengthValue.fromBigInt(publicKey.modulus),
+      BinaryLengthValue.fromBigInt(pk.exponent),
+      BinaryLengthValue.fromBigInt(pk.modulus),
     ]);
 
     if (comment.isNotEmpty) {
@@ -84,8 +79,7 @@ class RsaKeyPair {
   }
 
   String privateKeyString() {
-    var encrypter = RsaCrypt();
-    return encrypter.encodeKeyToString(privateKey);
+    return privateKey.toPEM();
   }
 
   static Future<RsaKeyPair> generateAsync() async {
@@ -102,30 +96,6 @@ class RsaKeyPair {
   }
 }
 
-SecureRandom _getSecureRandom() {
-  final secureRandom = FortunaRandom();
-  final random = Random.secure();
-  var seeds = List<int>.of([]);
-  for (var i = 0; i < 32; i++) {
-    seeds.add(random.nextInt(255));
-  }
-  secureRandom.seed(KeyParameter(Uint8List.fromList(seeds)));
-  return secureRandom;
-}
-
-///Create RSA keypair given SecureRandom.
-AsymmetricKeyPair<PublicKey, PrivateKey> _getRsaKeyPair(
-  SecureRandom secureRandom,
-) {
-  // See URL for why these values
-  // https://crypto.stackexchange.com/questions/15449/rsa-key-generation-parameters-public-exponent-certainty-string-to-key-count/15450#15450?newreg=e734eafab61e42f1b155b62839ccce8f
-  final rsapars = RSAKeyGeneratorParameters(BigInt.from(65537), 2048 * 2, 5);
-  final params = ParametersWithRandom(rsapars, secureRandom);
-  final keyGenerator = RSAKeyGenerator();
-  keyGenerator.init(params);
-  return keyGenerator.generateKeyPair();
-}
-
 FutureOr<RsaKeyPair> _gen(void _) async {
   return RsaKeyPair.generate();
 }

pubspec.lock

@@ -35,7 +35,7 @@ packages:
       name: asn1lib
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.6.4"
+    version: "0.8.1"
   async:
     dependency: transitive
     description:
@@ -162,6 +162,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "2.1.5"
+  crypton:
+    dependency: "direct main"
+    description:
+      name: crypton
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.3"
   csslib:
     dependency: transitive
     description:
@@ -759,7 +766,7 @@ packages:
       name: pointycastle
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.2"
+    version: "2.0.0"
   pool:
     dependency: transitive
     description:
@@ -953,7 +960,7 @@ packages:
       name: ssh_key
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.5.1"
+    version: "0.6.0"
   stack_trace:
     dependency: transitive
     description:
@@ -961,13 +968,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.10.0-nullsafety.1"
-  steel_crypt:
-    dependency: "direct main"
-    description:
-      name: steel_crypt
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.7.1+1"
   stream_channel:
     dependency: transitive
     description:

pubspec.yaml

@@ -41,13 +41,13 @@ dependencies:
   git_url_parse2: ^0.0.1
   synchronized: ^2.2.0
   mutex: ^1.0.3
-  steel_crypt: ^1.7.1+1
+  crypton: ^1.1.3
   font_awesome_flutter: ^8.7.0
   sentry: ">=3.0.0 <4.0.0"
   flutter_sentry: ^0.4.4
   equatable: ^1.1.0
   cached_network_image: ^2.2.0+1
-  ssh_key: ^0.5.1
+  ssh_key: ^0.6.0
   isolate: ^2.0.3
   image_picker: ^0.6.7
   easy_localization: ^2.3.2