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security

A stateless authentication service

Build token-based authentication with registration, login, refresh, and properly enforced route protection.

intermediateJava~26h

Why it matters

Nearly every backend role touches auth, and nearly every candidate describes it vaguely. Having implemented refresh and expiry yourself turns a vague answer into a specific one.

What you build

  • Registration with correctly hashed credentials
  • Login issuing a signed, expiring token
  • A refresh flow that does not extend forever
  • Route protection proven by tests, not by inspection

If you want more

  • Role-based authorisation
  • Token revocation on logout

Build it 5 steps

  • A modern adaptive hash with a per-user salt. Never a fast hash, never your own.

  • Build registration and login
  • Write tests that prove an unauthenticated request cannot get through

Material for the whole build

Shows applied security: correct hashing, token lifecycle, and enforcement verified by tests rather than assumed.

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