Envelope/mobile/lib/utils/storage/encryption_keys.dart

import 'package:shared_preferences/shared_preferences.dart';
import "package:pointycastle/export.dart";
import '/utils/encryption/rsa_key_helper.dart';

const rsaPrivateKeyName = 'rsaPrivateKey';

void setPrivateKey(RSAPrivateKey key) async {
    String keyPem = RsaKeyHelper.encodePrivateKeyToPem(key);

    final prefs = await SharedPreferences.getInstance();
    prefs.setString(rsaPrivateKeyName, keyPem);
}

Future<RSAPrivateKey> getPrivateKey() async {
    final prefs = await SharedPreferences.getInstance();
    String? keyPem = prefs.getString(rsaPrivateKeyName);
    if (keyPem == null) {
        throw Exception('No RSA private key set');
    }

    return RsaKeyHelper.parsePrivateKeyFromPem(keyPem);
}