Ditch the PKI: How to Go Truly Password less in a Hybrid World with Cloud Kerberos Trus
Article Summary / Key Takeaways: This article explains how IT admins can use Windows Hello for Business with the Cloud Kerberos Trust model to achieve true passwordless sign-in for hybrid environments. This method eliminates the need for a complex and costly on-premises Public Key Infrastructure (PKI), allowing users to access both cloud and on-prem resources seamlessly using biometrics or a PIN. Key benefits include lower maintenance, stronger security, and a unified user experience.
What is Windows Hello for Business?
Windows Hello for Business (WHfB) is a strong authentication method built into Windows. It replaces passwords with a secure, two-factor credential. Instead of a password, users log in with a:
- Fingerprint
- Facial scan (biometrics)
- Device-specific PIN
These credentials are asymmetric (a public/private key pair) and are bound to the device's hardware (TPM), making them highly resistant to phishing and credential theft.
The Old Problem: Why Was Hybrid Passwordless So Hard?
The main challenge for IT admins was on-premises resources. When a user tried to access an on-prem file share or app using their Windows Hello PIN, the on-prem Active Directory (AD) Domain Controllers (DCs) couldn't validate that credential.
The traditional solution was Certificate Trust. This required deploying a full Public Key Infrastructure (PKI) to issue certificates to every user and DC. This was a massive administrative burden, involving:
- Building and managing Certificate Authority (CA) servers.
- Handling certificate templates, issuance, and renewal.
- Dealing with complex certificate revocation lists (CRLs).
For many organizations, the cost and complexity of a hybrid PKI was a major roadblock.
The New Solution: What is Cloud Kerberos Trust?
Cloud Kerberos Trust is a modern deployment model for Windows Hello for Business that does not require a PKI.
Instead of your on-prem AD trusting certificates you issue, you configure your on-prem AD to directly trust Azure Active Directory (Azure AD).
When a user logs in with Windows Hello, Azure AD issues a partial Kerberos Ticket-Granting-Ticket (TGT). Because your on-prem Domain Controller trusts Azure AD, it accepts this ticket and issues a standard on-prem TGT. This allows the user to seamlessly access on-prem Kerberos resources (like file shares and apps) without a password and without a certificate.
How Does Cloud Kerberos Trust Work? (Step-by-Step)
Here is a simplified view of the authentication flow:
- User Sign-In: A user logs into their hybrid-joined Windows device using their fingerprint or PIN.
- Azure AD Validation: Windows contacts Azure AD, which validates the strong, device-bound Windows Hello credential.
- Azure AD Issues Ticket: Azure AD issues a partial Kerberos TGT (also called a "Cloud TGT") back to the device.
- On-Prem Resource Access: The user tries to access an on-prem file share. Windows presents the Cloud TGT to the on-prem Domain Controller (DC).
- DC Grants Access: Because the DC is configured with Cloud Kerberos Trust, it trusts the ticket from Azure AD. It then issues a normal on-prem TGT and service ticket, granting the user access.
The result is true, passwordless Single Sign-On (SSO) to both cloud and on-prem resources.
What Are the Benefits for IT Admins?
- Drastically Lower Maintenance: You completely eliminate the cost, complexity, and fragility of managing an on-prem PKI for user authentication.
- Seamless Hybrid Access: It bridges the gap between cloud and on-prem. Users get one simple, fast login for everything, from Microsoft 365 to legacy apps.
- Stronger Security & Compliance: This is a major security upgrade. It moves you to phishing-resistant MFA, helps you meet compliance requirements (NIST, CMMC, etc.), and aligns perfectly with a Zero Trust security model.
How Can NG Cloud Security Help?
While Cloud Kerberos Trust is simpler than a PKI, it is not a "single switch." A successful deployment requires careful planning, prerequisite checking, and configuration of the trust between Azure AD and your on-prem AD.
At NG Cloud Security, our team of Microsoft-certified experts specializes in deploying modern security and identity solutions. We help IT teams like yours:
- Assess your current hybrid environment.
- Configure the Cloud Kerberos Trust safely and efficiently.
- Create policies in Intune or GPO for a smooth user rollout.
- Achieve your passwordless goals without disrupting your business.
Frequently Asked Questions (FAQ)
Q: Do I need any new hardware for Cloud Kerberos Trust?
A: No. Cloud Kerberos Trust is a configuration-based solution. Your existing Domain Controllers (Windows Server 2016 or newer) and hybrid-joined client devices (with TPM 2.0) are supported.
Q: Does this replace my PKI completely?
A: It replaces the need for a PKI for user and device authentication. If you use a PKI for other services, like Wi-Fi (RADIUS) or VPN authentication, you may still need it for those specific use cases.
Q: What is the main difference between Cloud Kerberos Trust and Key Trust?
A: Key Trust was another model that still required a PKI to issue certificates to your Domain Controllers. Cloud Kerberos Trust is the first model that removes the PKI requirement entirely by creating a trust object directly in AD.
Q: Is this secure?
A: Yes. This is a highly secure, Microsoft-recommended solution. The authentication is based on strong, hardware-bound cryptographic keys and aligns with modern Zero Trust principles.
