About

Word of Wisdom DDOS Protected TCP Server with Proof of Work by Hashcash

The Task

Design and implement “Word of Wisdom” tcp server.

• TCP server should be protected from DDOS attacks with the Proof of Work (https://en.wikipedia.org/wiki/Proof_of_work), the challenge-response protocol should be used.
• The choice of the POW algorithm should be explained.
• After Proof Of Work verification, server should send one of the quotes from “word of wisdom” book or any other collection of the quotes.
• Docker file should be provided both for the server and for the client that solves the POW challenge

Why hashcash?

Hashcash is used for Proof of Work (PoW) because it requires a computationally expensive but easily verifiable process. This makes it effective for limiting spam, DoS attacks, and ensuring fairness in systems like Bitcoin. The key features are:

• Simple to Verify: The solution to a Hashcash challenge is easily checked by recalculating the hash.
• Costly to Compute: Generating a valid hash requires significant computational effort, deterring abuse.
• Adjustable Difficulty: The required number of leading zeros in the hash can be tuned to control the difficulty.

These properties make Hashcash ideal for establishing trust in decentralized systems.

Build and Test

make build-docker-client
make build-docker-server

Run

docker run --network=host wow-server -addr=":8089"
docker run --network=host wow-client -addr=":8089"