There is a web application that allows users to register by email and activate their account by the link in the email. And there is an application on android that communicates with the web application through json.
The goal is to enable users to register and log in to our web application through VC. On android, vk android sdk is used, user_id, token, and any personal information about the user (full name, gender, date of birth, etc.) is obtained during authorization on the client.
The question is - having this data, how can the server know exactly what is valid data? How to protect yourself from requests with random data that is “similar” to valid data? Indeed, in the case of registration by email, our guarantee of validity was a mandatory confirmation of the account by reference in the letter. And when registering for VC such a scheme is no longer. All traffic from the client to the server is open, not encrypted, easily intercepted by any sniffer (ie, you probably shouldn't send a token to the server).