Add RSA keys generation

ios/Classes/KeyGeneration.swift

@@ -7,6 +7,7 @@
 //  Author: Hugo Pointcheval
 //
 import Foundation
+import CommonCrypto
 
 class KeyGeneration {
     func keygen(size : NSNumber) -> Data? {
@@ -22,4 +23,37 @@ class KeyGeneration {
         }
         return nil
     }
+    
+    @available(iOS 10.0, watchOS 3.0, tvOS 10.0, *)
+    func rsaKeypairGen(size : NSNumber) throws -> [Data]? {
+        
+        let tagData = UUID().uuidString.data(using: .utf8)
+        
+        let isPermanent = true
+        
+        let attributes: [CFString: Any] = [
+            kSecAttrKeyType: kSecAttrKeyTypeRSA,
+            kSecAttrKeySizeInBits: (size.intValue * 8),
+            kSecPrivateKeyAttrs: [
+                kSecAttrIsPermanent: isPermanent,
+                kSecAttrApplicationTag: tagData!
+            ]
+        ]
+        
+        var error: Unmanaged<CFError>?
+        guard let privKey = SecKeyCreateRandomKey(attributes as CFDictionary, &error) else {
+            throw error!.takeRetainedValue() as Error
+        }
+        let pubKey = SecKeyCopyPublicKey(privKey)
+        
+        
+        var errorExport: Unmanaged<CFError>?
+        let data1 = SecKeyCopyExternalRepresentation(pubKey!, &errorExport)
+        let unwrappedData1 = data1 as Data?
+        
+        let data2 = SecKeyCopyExternalRepresentation(privKey, &errorExport)
+        let unwrappedData2 = data2 as Data?
+        
+        return [unwrappedData1!, unwrappedData2!]
+    }
 }

ios/Classes/SwiftNativeCryptoPlugin.swift

@@ -79,6 +79,31 @@ public class SwiftNativeCryptoPlugin: NSObject, FlutterPlugin {
                                 message: "GENERATED KEY IS NIL.",
                                 details: nil))
         }
+    case "rsaKeypairGen":
+        let args = call.arguments as! NSDictionary
+        
+        let size = args["size"] as! NSNumber
+        
+        let keypair : [Data]?
+        
+        if #available(iOS 10.0, *) {
+            do {
+                keypair = try KeyGeneration().rsaKeypairGen(size: size)
+            } catch {
+                keypair = nil
+            }
+        } else {
+            // Fallback on earlier versions
+            keypair = nil
+        }
+        
+        if keypair != nil {
+            result(keypair)
+        } else {
+            result(FlutterError(code: "KEYPAIRGENERROR",
+                                message: "GENERATED KEYPAIR IS EMPTY.",
+                                details: nil))
+        }
     case "encrypt":
         let args = call.arguments as! NSDictionary
         

lib/src/asym/RSA.dart

@@ -61,7 +61,7 @@ class RSAKeyEncapsulationMechanism implements KeyEncapsulationMechanism {
 
   @override
   Future<Encapsulation> encapsulate() {
-    if (!_isInit) {
+    if (!_isInit || _mode == KemMode.DECAPSULATION) {
       throw KemInitException("KEM not properly initialized.");
     }
     throw UnimplementedError();
@@ -69,6 +69,9 @@ class RSAKeyEncapsulationMechanism implements KeyEncapsulationMechanism {
 
   @override
   Future<SecretKey> decapsulate(Encapsulation encapsulation) {
+    if (!_isInit || _mode == KemMode.ENCAPSULATION) {
+      throw KemInitException("KEM not properly initialized.");
+    }
     throw UnimplementedError();
   }
 }

lib/src/platform.dart

@@ -99,7 +99,7 @@ class Platform {
   Future<List<Uint8List>> rsaKeypairGen(int size) async {
     try {
       final List<Uint8List> keypair =
-          await call('rsaKeypairGen', <String, dynamic>{
+          await callList('rsaKeypairGen', <String, dynamic>{
         'size': size,
       });
       return keypair;
@@ -146,8 +146,7 @@ class Platform {
     CipherParameters parameters,
   ) async {
     try {
-      final Uint8List data =
-          await _channel.invokeMethod('decrypt', <String, dynamic>{
+      final Uint8List data = await call('decrypt', <String, dynamic>{
         'payload': payload,
         'key': key,
         'algorithm': algorithm.name,