Universal 2FA platform

I have already built a platform that allows a consumer to register his mobile phone in the platform and to use it to authenticate transactions from third party website. I need a developer to develop an Android app to handle the functions at the consumer end. This app has two modes: a) Initially, the app allows the user to registers the device (i.e. mobile phone) in the platform. b) After registration, the app checks for messages from third party websites and sends a reply (accept, reject) to each message using the registered device. This replaces the traditional method where the third party website sends a SMS message with an OTP to the user. The user has to enter the OTP in the website to authenticate the transaction. Under this method, the third party website sends a message to the platform and the user uses the registered device to reply to the message. The requirements are spelled out here. [login to view URL] The following webpage shows the flow of the app. This was written for the developer to test the API and understand the flow. The developer needs to write the app to operate on an Android device. [login to view URL]