E2EEChat/lib/common/cipher.dart

import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:encrypt/encrypt_io.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:encrypt/encrypt.dart';
import 'package:path_provider/path_provider.dart';
import 'package:pointycastle/asymmetric/api.dart';

import 'global.dart';

Future<RSAPrivateKey?> getRSAPrivateKey(String username) async {
  try {
    final storage = FlutterSecureStorage();
    String? s = await storage.read(key: 'e2ee chat private key of $username');
    Directory tempDir = await getTemporaryDirectory();
    String tempPath = tempDir.path;
    String filePath = '$tempPath/public.pem';
    final file = File(filePath);
    final privateKey = await parseKeyFromFile<RSAPrivateKey>(filePath);
    file.delete();
    return privateKey;
  } catch (e) {
    debug('get rsa private key failed: $e');
  }
}

Future<RSAPublicKey?> getRSAPublicKey(String contents) async {
  try {
    Directory tempDir = await getTemporaryDirectory();
    String tempPath = tempDir.path;
    String filePath = '$tempPath/private.pem';
    final file = File(filePath);
    file.writeAsString(contents);
    final publicKey = await parseKeyFromFile<RSAPublicKey>(filePath);
    return publicKey;
  } catch (e) {
    debug('get rsa public key failed: $e');
  }
}