Identity & Access Management

Authentication vs Authorization

• Authentication (AuthN): Who are you?
• Authorization (AuthZ): What can you do?

OAuth 2.0 Flows

Authorization Code (Web Apps)

User -> App -> Auth Server -> User Login
User -> Auth Server -> App (code)
App -> Auth Server (code + secret) -> tokens

PKCE (Mobile/SPA)

Like Authorization Code but with code verifier/challenge instead of secret.

Client Credentials (Machine-to-Machine)

App -> Auth Server (client_id + secret) -> token

OpenID Connect (OIDC)

OAuth 2.0 + identity layer.

Key additions:

• ID Token (JWT with user info)
• UserInfo endpoint
• Standard claims (sub, email, name)

JWT Structure

header.payload.signature

Header: {"alg": "RS256", "typ": "JWT"}
Payload: {"sub": "123", "exp": 1234567890}
Signature: RSASHA256(header + payload, privateKey)

Role-Based Access Control (RBAC)

interface Role {
  name: string;
  permissions: Permission[];
}

interface Permission {
  resource: string;
  action: 'read' | 'write' | 'delete';
}

function hasPermission(user: User, resource: string, action: string): boolean {
  return user.roles.some(role =>
    role.permissions.some(p =>
      p.resource === resource && p.action === action
    )
  );
}

Best Practices

Passwords

• Minimum 12 characters
• Hash with Argon2id or bcrypt
• Never store plaintext
• Implement rate limiting

Sessions

• Use secure, HttpOnly cookies
• Implement CSRF protection
• Set appropriate expiration
• Invalidate on logout

Tokens

• Short-lived access tokens (15 min)
• Longer refresh tokens (days)
• Rotate refresh tokens
• Store securely (not localStorage)

MFA

• Support TOTP (Google Authenticator)
• Consider WebAuthn/passkeys
• Backup codes for recovery