## Purpose
This document outlines the Microsoft-recommended best practices for deploying a secure, internal-use-only, two-tier Public Key Infrastructure (PKI) using Windows Server 2022 or newer. The PKI supports securing S/MIME email, 802.1X Wi-Fi with NPS, and LDAP over SSL (LDAPS).

!!! abstract "Environment Breakdown"
    The environment will consist of at least 2 virtual machines.  For the purposes of this document they will be named `LAB-CA-01` and `LAB-CA-02`.  This stands for "*Lab Certificate Authority [01|02]*".  In a two-tier hierarchy, an offline (*you intentionally keep this VM offline*) Root CA signs a single "*Subordinate*" Enterprise CA certificate. The Subordinate CA is domain-joined and handles all certificate requests. Clients trust the PKI via Group Policy and Active Directory integration.

    In this case, `LAB-CA-01` is the Root CA, while `LAB-CA-02` is the Intermediary/Subordinate CA.  You can add more than one subordinate CA if you desire more redundancy in your environment.  Making them operate together is generally automatic and does not require manual intervention.

!!! note "Provisioning Assumptions"
    - OS = Windows Server 2022/2025 bare-metal or as a VM  
    - You should give it at least 4GB of RAM.  
    - [Change the edition of Windows Server from "**Evaluation**" to "**Standard**" via DISM](https://docs.bunny-lab.io/Workflows/Windows/Change%20Windows%20Edition/) 
    - Ensure the server is fully updated  
    - [Ensure the server is activated](https://docs.bunny-lab.io/Workflows/Windows/Change%20Windows%20Edition/#force-activation-edition-switcher)
    - Ensure the timezone is correctly configured
    - Ensure the hostname is correctly configured

### Offline (Non-Domain-Joined) Root CA `LAB-CA-01` Role Deployment
- Provision a **non-domain-joined** Windows Server
    - This is critical that this device is not domain-joined for security purposes
- Navigate to "**Server Manager > Manage > Add Roles and Features**"
    - Check "**Active Directory Certificate Services**"
        - When prompted to confirm, click the "**Add Features**" button
        - Ensure the "**Include management tools (if applicable)**" checkbox is checked.
    - Click "**Next**" > "**Next**" > "**Next**"
        - You will be told that the name of the server cannot be changed after this point, and it will be associated with `WORKGROUP` > This is fine and you can proceed.
    - Check the boxes for the following role services:
        - `Certification Authority`
        - `Certification Authority Web Enrollment`
            - When prompted to confirm multiple times, click the "**Add Features**" button
            - Ensure the "**Include management tools (if applicable)**" checkbox is checked.
                - There are additional steps such as `Configure AIA and CDP extensions with HTTP paths` and `Publish root cert and CRL to AD and internal HTTP`, but these do not apply to an LDAPS-only deployment, and are more meant for websites / webhosting.  (current understanding)
    - Click "**Next**" > "**Next**" > "**Next**" > "**Install**"
    - Restart the Server

### Offline (Non-Domain-Joined) Root CA `LAB-CA-01` Role Configuration
- Navigate to "**Server Manager > (Alert Flag) > Post-deployment Configuration: Active Directory Certificate Services**"
    - You will be prompted for an admin user, in this example, you will use the pre-populated `LAB-CA-01\Administrator`
    - Check the boxes for `Certification Authority` and `Certification Authority Web Enrollment` then click "**Next**"
    - Check the "**Standalone CA**" radio box then click "**Next**"
    - Check the "**Root CA** radio box then click "**Next**"
    - Check the "**Create a new private key**" radio box then click "**Next**"
    - Click the dropdown menu for "**Select a crypotographic provider**" and ensure that "**RSA#Microsoft Software Key Storage Provider**" is selected
        - *Microsoft Software Key Storage Provider (KSP) is the latest, most flexible provider designed to work with the Cryptography Next Generation (CNG) APIs. It offers better support for modern algorithms and improved security management (such as support for key attestation, better hardware integration, and improved key protection mechanisms).*
    - Set the key length to `4096`
    - Set the hash algorithm to `SHA256`
    - Click "**Next**"
    - **Common Name for this CA**: `BunnyLab-RootCA`
    - **Distinguished name suffix**: `O=Bunny Lab,C=US`
    - **Preview of distinguished name**: `CN=BunnyLab-RootCA,O=Bunny Lab,C=US`
    - Click "**Next**"
    - Specify the validity period: `10 Years` then click "**Next**" > "**Next**" > "**Configure**"

You will see a finalization screen confirming everything we have configured, it should look something like what is seen below:

| **Field** | **Value** |
| :--- | :--- |
| CA Type | Standalone Root |
| Cryptographic provider | RSA#Microsoft Software Key Storage Provider |
| Hash Algorithm | SHA256 |
| Key Length | 4096 |
| Allow Administrator Interaction | Disabled | 
| Certificate Validity Period | `<10 Years from Today>` |
| Distinguished Name | CN=BunnyLab-RootCA,O=Bunny Lab,C=US |
| Certificate Database Location | C:\Windows\system32\CertLog |
| Certificate Database Log Location | C:\Windows\system32\CertLog |

!!! success "Active Directory Certificate Services"
    If everything went well, you will see that the "**Certificate Authority**" and "**Certification Authority Web Enrollment**" both have a status of "**Configuration succeeded**".  At this point, you can click the "**Close**" button to conclude the Root CA configuration.

### Online (Domain-Joined) Subordinate/Intermediary CA `LAB-CA-02` Role Deployment
- Navigate to "**Server Manager > (Alert Flag) > Post-deployment Configuration: Active Directory Certificate Services**"
    - Under credentials, let it automatically populate a domain admin. (e.g. `BUNNY-LAB\nicole.rappe`)
    - Click "**Next**"
    - 

!!! warning "Under Construction"
    Section is still being written during lab deployment.

### Online (Domain-Joined) Subordinate/Intermediary CA `LAB-CA-02` Configuration Deployment
!!! warning "Under Construction"
    Section is still being written during lab deployment.

!!! warning "Raw Unprocessed Documentation - Do Not Use"
    3. Online Subordinate CA Setup
    Steps:
    1. Domain-join a Windows Server and install AD CS as Enterprise Subordinate CA.
    2. Generate CSR, sign with Root CA, import signed cert.
    3. Configure AIA/CDP extensions for CRL publication.
    4. Enable role separation and auditing.
    4. Certificate Templates and Autoenrollment
    Configure certificate templates for the following use cases:
        • - S/MIME Email: Use separate templates for signing and encryption. Enable key archival for encryption.
        • - 802.1X Wi-Fi: Use 'RAS and IAS Server' for NPS, and 'Workstation Authentication' for clients.
        • - LDAPS: Use 'Kerberos Authentication' template for domain controllers.
    Enable autoenrollment via GPOs under Public Key Policies for both Computer and User configuration.
    5. CRL and Revocation Management
    Publish CRLs regularly, configure overlap periods, and monitor expiration. Enable Delta CRLs on the Subordinate CA, but not on the Root.
    6. Security Recommendations
        • - Harden CA servers; limit access to PKI admins.
        • - Use BitLocker or HSM for key protection.
        • - Enforce strong cryptographic settings: RSA 2048+, SHA-256.
        • - Monitor issuance and renewals with audit logs and scripts.