generateKey method
Implementation
Future<File> generateKey({String password = '12345'}) async {
final arguments = [
'-in "${certificateP12.path}"',
'-nocerts',
'-out "${keyPem.path}"',
'-passin pass:',
'-passout pass:$password',
];
await run('openssl pkcs12 ${arguments.join(' ')}');
return keyPem;
}