Changed random seed generation for bitcoin.

lib/core/sec_random_native.dart

@@ -0,0 +1,13 @@
+import 'dart:typed_data';
+
+import 'package:flutter/services.dart';
+
+const utils = const MethodChannel('com.cake_wallet/native_utils');
+
+Future<Uint8List> secRandom(int count) async {
+  try {
+    return await utils.invokeMethod<Uint8List>('sec_random', {'count': count});
+  } on PlatformException catch (_) {
+    return Uint8List.fromList([]);
+  }
+}