Answer.

In the architecture of IT systems, security is implemented at several levels: authentication, authorization, encryption, auditing, and monitoring. A comprehensive implementation of these mechanisms is necessary — otherwise, a vulnerability in one link could jeopardize the entire system.

Main integration methods:

• Use encryption (Transport Layer Security, TLS) to protect traffic
• Implement centralized authentication: OAuth2, OpenID Connect
• Apply role-based authorization at the API and microservices level
• Audit and log access to critically important components

Example middleware for token (JWT) verification in Express.js:

const jwt = require('jsonwebtoken');

function authMiddleware(req, res, next) {
    const token = req.headers['authorization'];
    try {
        const decoded = jwt.verify(token, 'SECRET_KEY');
        req.user = decoded;
        next();
    } catch (e) {
        res.status(401).send('Unauthorized');
    }
}

Key features:

• Multi-layered (defense-in-depth) security strategy
• Minimum access rights (principle of least privilege)
• Reliable key rotation, secret encryption and access control

Trick questions.

Is it enough to use HTTPS for complete protection of API traffic?

No, HTTPS protects transmissions, but does not guarantee the absence of vulnerabilities in endpoints or data storage security.

Is OAuth2 a standalone authentication system?

No, OAuth2 is an authorization protocol; to obtain user identification, OpenID Connect is used on top of OAuth2.

Can we solely trust third-party services (e.g., IAM) for access management?

No, a second level of control within the application is always needed (e.g., RBAC/ABAC), as errors in external systems can expose critical resources to unauthorized access.