How to uniquely identify a smartphone?

Question

PHP

There is some application on android that sends data to the server. The task of the server is to store this data. Each packet sent to the server has a user signature (in fact, JSON is sent in which there is a user ID). The server stores a bunch of IMEI and user ID. It is necessary that the server be able to determine that this data was actually sent from the smartphone whose IMEI was specified in the packet. How to implement such a task?

Answer 1

There will be no 100% guarantee in any case, you can increase the likelihood and complicate the life of a hacker by sending a request signed with an electronic signature (see digital signature), but even in this case, if the attacker has access to the device from which the data was sent, then there will not be much problems to bypass this.
it is impossible to understand "on request" that it was the phone that sent it, because bytes are bytes, they can be overheard, corrected and sent corrected

Answer 2

Maybe this option is suitable for getting IMEI: How to programmatically get the devices IMEI/ESN i... ?