Zero Trust Security Model - sonuprajapati15/Authentication-Authorization GitHub Wiki

System Design: Zero Trust Security Model

1. Overview

The Zero Trust Security Model (ZTSM) is a security framework that assumes no entityβ€”inside or outside the networkβ€”should be trusted by default. Every request must be verified, authenticated, and continuously monitored before access is granted.

πŸ”Ή Core Principle: "Never Trust, Always Verify."

πŸ”Ή Why Zero Trust?
βœ… Prevents insider threats and lateral movement of attackers.
βœ… Protects against data breaches and unauthorized access.
βœ… Enforces least privilege access for users, devices, and applications.


2. Functional & Non-Functional Requirements

Functional Requirements

βœ… Identity Verification – Authenticate users with Multi-Factor Authentication (MFA).
βœ… Device Trust – Ensure only secure, compliant devices can access resources.
βœ… Least Privilege Access – Grant access dynamically based on policies.
βœ… Continuous Monitoring – Analyze user behavior and re-evaluate access.
βœ… Micro-Segmentation – Restrict lateral movement between network resources.
βœ… Logging & Auditing – Track all access requests for security analytics.

Non-Functional Requirements

⚑ Security – Enforce end-to-end encryption, strong authentication, and anomaly detection.
⚑ Scalability – Support large-scale deployments across cloud and on-premise environments.
⚑ Performance – Minimize authentication delays with caching and smart policies.
⚑ Compliance – Ensure GDPR, HIPAA, SOC2 compliance for security and privacy.
⚑ Flexibility – Adapt to hybrid and multi-cloud environments.


3. High-Level Design (HLD)

Architecture Components

  1. Identity Provider (IdP) – Authenticates users and enforces MFA.
  2. Policy Decision Point (PDP) – Evaluates access policies dynamically.
  3. Policy Enforcement Point (PEP) – Intercepts requests and verifies authorization.
  4. Device Trust Engine – Ensures that only secure devices can access resources.
  5. Behavioral Analytics – Uses AI/ML to detect anomalous activity.
  6. Micro-Segmentation Controller – Restricts lateral movement within networks.
  7. Logging & Security Information and Event Management (SIEM) – Monitors access logs for threats.

Zero Trust Workflow

  1. User requests access β†’ Sends request with credentials & device info.
  2. Identity & Device Verification β†’ MFA + Device Trust Check.
  3. Policy Evaluation β†’ The system checks role, device, location, risk score.
  4. Access Decision β†’ If conditions are met, access is granted with least privilege.
  5. Continuous Monitoring β†’ Behavior is analyzed for suspicious activity.
  6. Dynamic Enforcement β†’ If risk is detected, access is revoked or re-authenticated.

4. Low-Level Design (LLD)

Database Schema

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    username VARCHAR(255) UNIQUE NOT NULL,
    password_hash TEXT NOT NULL,
    role VARCHAR(50),
    mfa_enabled BOOLEAN DEFAULT TRUE
);

CREATE TABLE devices ( id SERIAL PRIMARY KEY, user_id INT REFERENCES users(id) ON DELETE CASCADE, device_id VARCHAR(255) UNIQUE NOT NULL, os VARCHAR(50), last_seen TIMESTAMP );

CREATE TABLE access_policies ( id SERIAL PRIMARY KEY, role VARCHAR(50) NOT NULL, resource VARCHAR(255) NOT NULL, condition TEXT NOT NULL );

CREATE TABLE access_logs ( id SERIAL PRIMARY KEY, user_id INT REFERENCES users(id), resource VARCHAR(255), action VARCHAR(50), timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP, status VARCHAR(20) );

Policy Examples

Role Resource Condition Rule Explanation
Admin /admin-panel Device is corporate-managed Only secure devices can access admin panel
HR /payroll Location is corporate network HR staff can only access payroll from office
User /sensitive-doc MFA is verified Users need MFA for sensitive files
Manager /dashboard Risk Score < 50 Managers with normal behavior can access

6. Diagrams

Zero Trust Security Flow

View or edit this diagram in Whimsical.


7. Code Implementation (Node.js + Express + JWT + Zero Trust Policies)

1. Install Dependencies

npm install express bcrypt jsonwebtoken dotenv

2. Setup Express Server with Zero Trust Policies

require("dotenv").config();
const express = require("express");
const bcrypt = require("bcrypt");
const jwt = require("jsonwebtoken");

const app = express(); app.use(express.json());

// Mock Users & Policies const users = [ { id: 1, username: "admin", passwordHash: bcrypt.hashSync("password", 10), role: "admin", mfaEnabled: true, deviceTrusted: true } ];

const zeroTrustPolicies = [ { resource: "/admin-panel", condition: "mfa_verified && device_trusted" }, { resource: "/sensitive-doc", condition: "mfa_verified" } ];

// Zero Trust Middleware const authorize = (resource) => (req, res, next) => { const token = req.headers.authorization?.split(" ")[1]; const user = jwt.verify(token, process.env.JWT_SECRET); const policy = zeroTrustPolicies.find(p => p.resource === resource);

if (!policy || !(user.mfaVerified && user.deviceTrusted)) { return res.status(403).json({ message: "Access Denied" }); } next(); };

// Protected Route app.get("/admin-panel", authorize("/admin-panel"), (req, res) => res.json({ message: "Admin Panel Access Granted" }));

app.listen(3000, () => console.log("Zero Trust Server running on port 3000"));



5. Trade-offs & Scalability

Factor Trade-off
Security Strongest security model, but requires careful policy management.
Performance Continuous verification may slow requests; caching helps.
Flexibility Adapts to hybrid environments, but complex to implement.
Scalability Works well for enterprises, but requires distributed enforcement points.

8. Conclusion

The Zero Trust Security Model provides the highest level of security by ensuring continuous authentication & least privilege access. It is ideal for enterprise, government, and cloud security.

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