import { Callout, Cards, Card } from 'nextra/components'
import { ShieldCheck, ShieldAlert, BadgeCheck, Lock, Key, Link, CheckCircle2, XCircle } from 'lucide-react'

# PKI Fundamentals & Trust Context

**Public Key Infrastructure (PKI)** is the framework that allows secure communication over the internet. It relies on cryptographic keys and a chain of trust to verify identities.

## Core Concepts

Understanding these two mechanisms is essential to understanding how TrustLab works.

### 1. Asymmetric Encryption
Secure communication relies on a pair of keys:
*   <Key className="inline w-4 h-4 mr-1"/> **Public Key**: Shared with everyone. Used to **encrypt** data.
*   <Lock className="inline w-4 h-4 mr-1"/> **Private Key**: Kept secret. Used to **decrypt** data and **sign** digital assets.

### 2. The Chain of Trust
A certificate is only trusted if it is signed by a known authority. This forms a chain:
*   **Root CA**: The trusted anchor. It signs itself. You must install this on your device to trust the chain.
*   **Intermediate CA**: Signed by the Root CA. Used to sign day-to-day certificates for security.
*   **Leaf Certificate**: The final certificate used on your Web Server or Email.

---

## The Two Lanes of Trust

The internet security model is built on two distinct "lanes". Mixing them up causes browser errors, but using them correctly provides **Military-Grade Security**.

<Cards>
  <Card icon={<ShieldCheck />} title="Public Lane (Global)" href="#public-pki" arrow />
  <Card icon={<Lock />} title="Private Lane (Internal)" href="#private-pki-trustlab" arrow />
</Cards>

### Public PKI
*   **Issuer**: Let's Encrypt, DigiCert, Google Trust Services.
*   **Trust Model**: Pre-installed in every browser/OS (Chrome, Windows, iOS) by default.
*   **Limitation**: **Cannot** issue certificates for Private IPs (`192.168.x.x`) or Internal Domains (`.local`, `.lan`).

### Private PKI (TrustLab)
*   **Issuer**: TrustLab Root CA (Your Organization).
*   **Trust Model**: Trusted **ONLY** by devices that have explicitly installed your Root CA.
*   **Superpower**: Can secure **ANYTHING** internal (Localhost, Database Servers, IoT).

---

## Why "Military Grade"?

TrustLab utilizes **OpenSSL**, the same cryptographic core used by the world's highly secure networks.

| Feature | TrustLab (Private) | Public CA (Paid) |
| :--- | :--- | :--- |
| **Encryption** | RSA-2048 / RSA-4096 | RSA-2048 / RSA-4096 |
| **Signature** | SHA-256 | SHA-256 |
| **Protocol** | TLS 1.2 / 1.3 | TLS 1.2 / 1.3 |
| **Global Trust** | <XCircle className="inline w-4 h-4 text-red-500"/> (Manual Install) | <CheckCircle2 className="inline w-4 h-4 text-green-500"/> (Pre-installed) |
| **Internal IPs** | <CheckCircle2 className="inline w-4 h-4 text-green-500"/> Supported | <XCircle className="inline w-4 h-4 text-red-500"/> Forbidden |
| **Cost** | **Free** | $400+/month (Private CA) |

## Appropriate Use Cases

<Callout type="info" emoji={<BadgeCheck className="w-5 h-5" />}>
  **The Golden Rule:**
  Use **TrustLab** for anything the Public Internet CANNOT access.
  Use **Public CAs** for anything the Public Internet MUST access.
</Callout>

### <CheckCircle2 className="inline w-5 h-5 text-green-500 mr-2"/> Perfect For (Green Lane)
*   **Internal Tools**: Admin Panels, HR Portals, Dashboards.
*   **Development**: Testing HTTPS on `localhost` or `dev.local`.
*   **Databases**: Securing connections to MySQL/Postgres/Mongo.
*   **S/MIME**: Encrypting email between internal employees.

### <XCircle className="inline w-5 h-5 text-red-500 mr-2"/> Do Not Use For (Red Lane)
*   **Public E-Commerce**: Your customer's browser will show a "Not Secure" warning.
*   **Public Blogs/Websites**: Random visitors do not have your Root CA installed.

## The "Trust Split" Myth

There is **no conflict** between having TrustLab installed and visiting public websites.
*   When you visit `google.com`, your browser uses the **Public Lane**.
*   When you visit `intranet.corp`, your browser sees the TrustLab signature and uses the **Private Lane**.

They coexist peacefully, providing comprehensive security for your entire digital life.
