The enterprise perspective on authentication: FIDO2 vs. PKI

As a CISO, you are tasked with protecting your organization's most critical assets, while ensuring operational efficiency and agility. At the core of this challenge is enterprise identity management. In this post, we examine the evolution of the authentication landscape by comparing traditional PKI smartcard-based methods with the emerging FIDO2 standard, focusing on hardware-backed security, user experience, and strategic alignment with enterprise priorities. 

The shifting landscape of authentication 

The post-pandemic world has fundamentally reshaped the boundaries of enterprises. Remote work, cloud-first strategies, and growing reliance on third-party services have redrawn enterprise boundaries and widened the attack surface. Authentication—once a network checkpoint behind VPNs and perimeter defenses—has become a strategic control point. In open, distributed environments, anyone who can authenticate can access, making assurance the new perimeter.

At the same time, organizations must cut costs and simplify operations. Legacy systems remain secure but demand heavy maintenance. The goal is clear: strengthen security while improving usability and minimizing friction.

Balancing security, usability, and productivity is essential for long-term success.

Regulations such as NIS2, eIDAS, NIST, and ISO now heighten the urgency, pushing enterprises to treat authentication not as an IT function but as a core element of risk management.

Also read: Step 1 to NIS2 compliance - Get started with MFA 

Why hardware-backed authentication is foundational 

Hardware-backed authentication, whether using PKI smartcards or FIDO2 security keys, anchors credentials in tamper-resistant devices, ensuring high assurance and minimizing credential theft. 

Key benefits: 

• Cryptographic attestation without sharing secrets 

• Private keys stored securely in hardware 

• Protection against phishing and replay attacks 

• Local verification without network dependency 

This model aligns with Zero Trust principles, making hardware-backed MFA the gold standard for strong access control. By binding credentials to a physical device, the attack surface shrinks to a single, verifiable point. 

Both PKI and FIDO2 follow this principle—trust rooted in physical possession and cryptographic integrity. 

Also read: Is Zero-trust strategy the answer to growing security concerns?

Credential lifecycle management: The prerequisite to any authentication strategy 

Before comparing PKI and FIDO2, it’s essential to address credential lifecycle management. Regardless of the method—smartcards, FIDO keys, or any other—automated processes for issuing, revoking, and updating credentials are critical. Without them, security gaps and operational inefficiencies will inevitably emerge. 

In addition to being an indispensable security requirement, credential lifecycle management is vital for scalability. Manual administration is unsustainable at enterprise scale. Whether you choose PKI, FIDO2, or a hybrid approach, robust lifecycle management must be in place to ensure your authentication strategy is secure, efficient, and future-ready. 

PKI: A proven and versatile standard 

Public Key Infrastructure (PKI) has been at the foundation of enterprise security for decades. It supports a wide range of use cases, including authentication, encryption, and digital signing. 
 

Key highlights of PKI 

• Mature and widely adopted across critical infrastructure sectors 

• Based on asymmetric cryptography using public and private key pairs 

• Commonly deployed via smartcards and other secure hardware 
• Supports both authentication and non-authentication use cases 
   

How PKI works
At its core, PKI relies on asymmetric cryptography. When a PKI credential is created and stored on a smartcard, a key pair is generated: 

• The private key is generated on the smartcard and remains securely stored on the chip and is never shared. 

• The public key is included in a certificate signing request (CSR), which is sent to a Certificate Authority (CA). 

The CA verifies the user's identity and signs the certificate, confirming that the public key belongs to the individual. This signed certificate, paired with the private key, enables secure identity verification.

Authentication in action

1. The user attempts to log in to a service. 
2. The service sends a challenge. 
3. The user signs the challenge using the private key stored on the smartcard. 
4. The signed challenge and certificate are returned to the service. 
5. The service uses the public key from the certificate to validate the signature. 
6. If the signature is valid, the user is authenticated. 

This process ensures that only the person in possession of the smartcard (and its private key) can successfully authenticate. 

An important step in this process is certificate validation. The service checks with the CA to confirm that the certificate is still valid and hasn’t been revoked—typically using OCSP (Online Certificate Status Protocol) or CRLs (Certificate Revocation Lists). 

Enterprise considerations 

PKI offers several strategic advantages: 

• Centralized revocation: Managed by a single CA, making it easier to maintain trust across multiple services using the same credential. 

• Built-in identity binding: The CA handles identity verification, enabling a native system for binding credentials to verified identities. 

• Industrialized processes: PKI is well-documented and standardized, with established playbooks for large-scale enterprise deployment. 

However, smart card based PKI also introduces complexity: 

• Requires smartcard readers and infrastructure for certificate issuance and renewal. 

• Demands administrative overhead and lifecycle management. 

• Best suited for organizations with existing PKI expertise and structured IT environments. 

For large, regulated enterprises needing authentication, signing, and encryption in one solution, PKI remains the most comprehensive option. 

Also read: [Trend report] PKI evolution in cybersecurity

FIDO2: A new approach to authentication 

FIDO2 introduces a passwordless, phishing-resistant authentication model developed by leading technology companies to address long-standing weaknesses in user authentication. Designed for usability and scalability, FIDO2 delivers strong security with minimal user friction—making it an increasingly popular choice for modern enterprises. 

Like PKI, FIDO2 leverages public key cryptography and hardware-backed credentials. However, it simplifies the user experience and enhances protection against phishing and credential theft. 

Key highlights of FIDO2 

• Streamlined user experience with no passwords to manage 

• Easy deployment and lifecycle management 

• Strong resistance to phishing and credential theft 

• Most common hardware form factor is a USB security key, though other options exist 
• Supports both roaming authenticators and platform authenticators 

How FIDO2 Works
FIDO2 is backed by widespread industry support, with major tech companies contributing to its development and integration. As a result, FIDO2 standards are embedded in modern operating systems, mobile platforms, and online services. 

FIDO2 is built on two core standards: 

• CTAP (Client to Authenticator Protocol): Governs communication between the device and the authenticator (e.g., USB key interaction). 

• WebAuthn (Web Authentication): Handles the authentication process within web applications. 

Registration and authentication flow 

FIDO2 authentication is conceptually similar to PKI. 

• A key pair is generated directly on the authenticator during registration. 

• The private key remains securely stored on the device and is never shared. 

But with a key distinction: 

• The public key is sent to the service and linked to the user’s account. 

Unlike PKI, FIDO2 credentials are domain-specific: 

• Each service requires its own key pair. 

• During authentication, the service sends a challenge along with its domain. 

• The authenticator responds only if it has a matching key pair for that domain. 

This domain-bound model significantly reduces the risk of credential misuse across services. But it can also add to complexity as you need your own key pair for each service. 

Enterprise considerations 

FIDO2 offers compelling benefits: 

• Passwordless experience improves usability and reduces attack vectors. 

• Hardware-backed credentials enhance security without transmitting secrets. 

• Aligns well with modern, cloud-based, bring-your-own-device (BYOD) environments. 

However, FIDO2 is still maturing: 

• Integration with legacy systems and enterprise workflows may require additional planning. 

• Issuance, control, and lifecycle processes are less standardized than PKI. 

• Identity binding is not built-in; it relies on a strong Identity Provider (IdP) to manage federated access. 

In practice, users often register FIDO credentials with their IdP, which then enables single sign-on (SSO) or federation across services. This makes the IdP a central trust anchor—its reliability and security become critical. 

To balance innovation with operational continuity, many organizations adopt hybrid models that combine FIDO2 with existing authentication frameworks. 

Also read: FIDO2 and the rise of passwordless authentication

Authentication that moves business forward 

With the authentication landscape rapidly evolving, now is the time to reassess your security strategy. Whether you're reinforcing PKI, evaluating FIDO2, or exploring hybrid models, your identity architecture must be equipped to meet emerging threats and growing compliance demands. 

If you are still relying on passwords, it is indisputable that they must be replaced—promptly. Passwords are no longer sufficient to protect modern enterprises. Continuing to use them puts your business at serious risk. 

Start by reviewing your current authentication methods: 

• Are they scalable across your workforce? 

• Do they provide the level of security your risk profile demands? 

• Are they frictionless enough to support user adoption? 

• Are they aligned with regulations like NIS2? 

Engage with your security teams, identity providers, and stakeholders to define a roadmap that balances assurance with agility. The decisions you make today will shape your organization’s resilience tomorrow. 
 

Choosing the right model 

Both PKI and FIDO2 are excellent options for strong authentication. If your use cases include digital signing or encryption, PKI is the better fit—it’s mature, widely adopted, and supports a broader range of enterprise-grade functions. 

FIDO2, on the other hand, offers a streamlined user experience and is ideal for passwordless authentication. It’s device-agnostic, easy to deploy, and well-suited for modern, cloud-first environments. 

And yes, you can have both. Hybrid approaches are increasingly common. For example, some security keys support both FIDO2 for authentication and PKI certificates for signing and encryption. This flexibility allows you to tailor your strategy to different user groups and business needs. 

View complete comparison: FIDO vs. PKI

One vendor, full lifecycle 

Minimizing complexity and fragmentation is key. A single-vendor approach reduces the “security tax” that comes from managing multiple systems, even when they are standards-based. 

At Nexus, we offer full lifecycle support for both FIDO2 tokens and PKI smartcards —giving organizations the flexibility to choose, combine, or transition between authentication models as needed. Whether you are issuing USB security keys for passwordless login or smartcards for signing and encryption, we provide a unified platform to manage it all. 

From credential issuance and self-service onboarding to mobile IDs, automated revocation, and identity provider integration—we help enterprises manage identity at scale. Our solutions support hybrid environments, enabling seamless coexistence of FIDO2 and PKI within a single infrastructure. 

Let’s build authentication that works, for your users, your infrastructure, and your future.