A method comprising: receiving , by one or more servers , a data request comprising one or more attributes characterizing an environment of a client device to which requested data will be provided; selecting , by the one or more servers, response data based on the one or more attributes; generating , by the one or more servers and including the one or more attributes characterizing the environment of the client device to which the requested data will be provided, a validation challenge that controls access to the response data based on whether the client device generates a correct answer to the validation challenge, including: providing the client device access to the response data when the answer generated by the client device correctly responds to the validation challenge and the client device matches the one or more attributes of the environment specified in the validation challenge with the one or more attributes of the environment specified in the data request; preventing the client device from accessing the response data when the answer generated by the client device does not correctly respond to the validation challenge or the client device does not match the one or more attributes of the environment specified in the validation challenge with the one or more attributes of the environment specified in the data request; and securing , by the one or more servers, the response data with the validation challenge; and transmitting , by the one or more servers, the response data secured with the validation challenge to the client device. receiving , by one or more servers , a data request comprising one or more attributes characterizing an environment of a client device to which requested data will be provided; selecting , by the one or more servers, response data based on the one or more attributes; generating , by the one or more servers and including the one or more attributes characterizing the environment of the client device to which the requested data will be provided, a validation challenge that controls access to the response data based on whether the client device generates a correct answer to the validation challenge, including: providing the client device access to the response data when the answer generated by the client device correctly responds to the validation challenge and the client device matches the one or more attributes of the environment specified in the validation challenge with the one or more attributes of the environment specified in the data request; preventing the client device from accessing the response data when the answer generated by the client device does not correctly respond to the validation challenge or the client device does not match the one or more attributes of the environment specified in the validation challenge with the one or more attributes of the environment specified in the data request; and providing the client device access to the response data when the answer generated by the client device correctly responds to the validation challenge and the client device matches the one or more attributes of the environment specified in the validation challenge with the one or more attributes of the environment specified in the data request; preventing the client device from accessing the response data when the answer generated by the client device does not correctly respond to the validation challenge or the client device does not match the one or more attributes of the environment specified in the validation challenge with the one or more attributes of the environment specified in the data request; and securing , by the one or more servers, the response data with the validation challenge; and transmitting , by the one or more servers, the response data secured with the validation challenge to the client device. <EOS>