TCP server Server returns random quote from "Quotes storage" Server has DDOS protect with captcha
Client->Server:Get
Server-->Client:Captcha task
Client->Server:Captcha solution
Note right of Server: Validating solution
Server-->Client:authentication time signature
Client->Server:Get quotes with authentication code
Server-->Client: quotes
Server sends the value, signature for value and precision for solving task
Client has to find nonce that hash of value+nonce less then required value
The precision can be implemented with dynamic changing to satisfying number of request handled by server
It's time based signature, so it expires at configured time