Introduction to Web3 Security

Web3 security is different from traditional app security because transactions are irreversible, code is public, and anyone on the internet can become an adversary. There is no support desk that can undo a signed transfer or reverse a malicious approval once it confirms on-chain.

Most losses are not caused by broken cryptography. They come from social engineering, careless signing, unsafe contract design, and trust placed in bridges or admin keys without understanding the tradeoffs.

This course covers both sides of the problem: what users must do to protect themselves, and what builders must do to ship contracts and infrastructure that do not become single points of failure.

Treat security as a habit, not a one-time setup. The chapters ahead walk through threat modeling, wallet hygiene, contract risks, and the mindset that keeps you skeptical when everything looks legitimate.