message_list_view.dart

    MessageListView(
      messageBuilder: _messageBuilder,
    )
    -----------
    Widget _messageBuilder(
      BuildContext context,
      MessageDetails details,
      List<Message> messages,
    ) {
      Message message = details.message;
      final isCurrentUser = StreamChat.
    (context).user.id == message.user.id;
      final textAlign = isCurrentUser ? TextAlign.right : TextAlign.left;
      final color = isCurrentUser ? Colors.
    : Colors.
    ;
      return FutureBuilder<String>(
        future: AppE2EE().decrypt(message.text), // a Future<String> or null
        builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.none:
            case ConnectionState.waiting:
            default:
              if (snapshot.hasError)
                return Text('Error: ${snapshot.error}');
              else
                return Padding(
                  padding: EdgeInsets.all(5.0),
                  child: Container(
                    decoration: BoxDecoration(
                      border: Border.all(color: color, width: 1),
                      borderRadius: BorderRadius.all(
                        Radius.circular(5.0),
                      ),
                    ),
                    child: ListTile(
                      title: Text(
                        snapshot.data,
                        textAlign: textAlign,
                      ),
                    ),
                  ),
                );
          }
        },
      );
    }