Authentication answers the question "Who are you?" It's the first step in access control, followed by authorization (what you can do) and accounting (logging your actions).
Why it matters
- Without authentication, anyone could access sensitive systems and data.
- Weak authentication is the root cause of most data breaches.
- Compliance frameworks (HIPAA, PCI-DSS, SOC 2) require strong authentication controls.
- Modern zero-trust architectures rely on continuous authentication.
Authentication factors
- Something you know: Passwords, PINs, security questions.
- Something you have: Security keys, authenticator apps, smart cards, SMS codes.
- Something you are: Biometrics like fingerprints, facial recognition, iris scans.
- Somewhere you are: Location-based verification, IP restrictions.
- Something you do: Behavioral biometrics like typing patterns.
Common authentication methods
- Password-based: Most common but weakest—vulnerable to phishing, credential stuffing.
- Multi-factor authentication (MFA): Combines two or more factors for stronger security.
- Single sign-on (SSO): One login grants access to multiple applications.
- Certificate-based: Uses digital certificates for mutual authentication.
- Token-based: JWTs, OAuth tokens for stateless authentication.
- Passwordless: FIDO2/WebAuthn security keys, magic links, biometrics.
Best practices
- Implement MFA everywhere, especially for privileged accounts.
- Use password managers and enforce strong password policies.
- Prefer phishing-resistant methods like hardware security keys.
- Monitor for credential stuffing and brute force attacks.
- Implement account lockout and rate limiting.
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