Passkeys replace shared secrets with asymmetric cryptography, while multifactor authentication adds extra proof of identity to an existing sign-in method. In practice, passkeys can reduce reliance on passwords, but they do not eliminate the need for layered controls in every context. Many organisations use them together for step-up authentication or higher-risk access paths.
Why Passkeys and Multifactor Authentication Solve Different Problems
Passkeys and multifactor authentication are often discussed together, but they change the access model in different ways. Passkeys replace reusable shared secrets with phishing-resistant cryptographic credentials, while multifactor authentication adds extra proof on top of a primary sign-in method. The practical difference matters because one is fundamentally a credential architecture shift and the other is a strengthening layer that can still sit on top of passwords or other weak first factors.
That distinction is important in modern access strategy because organisations are trying to reduce phishing, credential replay, and password reuse without overcomplicating user access. A passkey can remove a whole class of password-based failure, but MFA still has value where a system needs step-up checks, recovery paths, or protection for especially sensitive actions. The two controls are not interchangeable, and treating them as if they are leads to gaps in policy design and user experience.
Current guidance and industry practice increasingly favour passkeys for primary authentication where supported, while keeping MFA or equivalent step-up controls for higher-risk events. In practice, many security teams discover the difference only after they have already built policies that assume every second factor meaningfully improves protection.
How They Work in a Modern Access Flow
A passkey uses asymmetric cryptography bound to a device or authenticator. During login, the service verifies a signed challenge rather than comparing a secret the user types in. That design makes passkeys resistant to phishing and credential stuffing because there is no reusable password to steal and replay. For many users, the passkey becomes the first and often only routine sign-in method.
MFA works differently. It asks for an additional proof, such as a time-based code, push approval, biometric check, hardware token, or recovery factor, after the primary factor is presented. MFA can improve security significantly, but its strength depends on the factor type and how the flow is implemented. Some MFA methods remain vulnerable to interception, prompt bombing, or social engineering, especially when the first factor is a password that can still be phished.
- Passkeys are best understood as a replacement for shared secrets in the primary authentication step.
- MFA is best understood as a layered verification method that can apply before, during, or after access depending on risk.
- In a modern access strategy, passkeys often reduce routine login friction, while MFA remains useful for recovery, privilege elevation, or unusual sign-in conditions.
The architectural choice is less about whether a user sees one prompt or two, and more about whether the organisation is still depending on reusable secrets as the foundation of trust. For that reason, a passkey-first strategy usually works best when paired with risk-based policies, device trust signals, and tightly governed fallback methods. These controls tend to break down when legacy systems still require password recovery, shared admin access, or inconsistent support for authenticator portability.
Where the Tradeoffs Appear in Real Deployments
Tighter authentication can improve security, but it can also create operational friction if organisations assume one mechanism covers every use case. Passkeys are strongest when the service and the user’s device ecosystem support them cleanly, yet they may not fit every shared workstation, service desk workflow, or regulated recovery process. MFA is broader in coverage, but some MFA methods are weaker than teams expect, especially if they are treated as a substitute for eliminating passwords.
For that reason, current guidance suggests using passkeys for primary human authentication where possible, then reserving MFA for step-up events, recovery, and exceptional access. That approach recognises that not every authentication event has the same risk profile. High-risk actions such as credential changes, finance approvals, or privileged admin tasks often still need a separate assurance step even if the user signed in with a passkey.
Practitioners should also separate user authentication from machine and service access. A passkey strategy does not solve secrets sprawl, workload identity, or service-to-service authentication. Those areas still need their own governance, because the modern access stack usually has both human and non-human identities in play. If teams blur those layers, they may overestimate the protection offered by user login improvements and under-govern the systems that actually hold operational access.
Risk and Threat Considerations
The main risk is mistaking a stronger login method for a complete access strategy. Passkeys reduce phishing exposure for human users, but they do not automatically address fallback recovery, session theft, privileged workflows, or non-human identities that still authenticate with secrets. MFA reduces exposure when applied well, but weak or easily phishable second factors can still be bypassed by social engineering or real-time relay attacks.
Failure mechanism: Risk materialises when organisations keep password recovery, SMS-based verification, shared admin accounts, or weak fallback channels in place after deploying passkeys. Attackers then target the weakest remaining path rather than the strongest primary login method, and the access model still depends on one compromised factor, one recovery flow, or one trusted device pathway.
Impact: The result is inconsistent assurance across the environment. Users may enjoy stronger sign-in protection while privileged access, account recovery, or service access remains exposed, creating a false sense of security and a broader attack surface than policy owners expect.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 address the attack and risk surface, while NIST SP 800-63, NIST Zero Trust (SP 800-207) and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 — Inventory and Ownership | Passkeys and fallback credentials must be inventoried and owned to avoid hidden access paths. |
| NHI-03 — Secrets and Credential Management | Passkeys replace reusable secrets, while MFA and recovery still hinge on credential handling. | |
| Recommendation — Inventory all authentication methods and assign ownership for fallback and recovery paths. Remove reusable secrets where possible and govern recovery credentials tightly. | ||
| NIST SP 800-63 | AAL — Authenticator Assurance Level | The question compares primary authentication strength and step-up assurance. |
| Recommendation — Map passkeys and MFA flows to the required assurance level for each access path. | ||
| NIST Zero Trust (SP 800-207) | Policy Decision Point — Policy Decision Point | Modern access strategy should evaluate context and risk before granting access. |
| Recommendation — Apply real-time policy checks before granting access or step-up privileges. | ||
| CIS Controls v8 | 6.3 — Access Granting and Revocation | Passkeys and MFA both depend on tightly managed account access and recovery controls. |
| Recommendation — Enforce least privilege and promptly revoke access paths that are no longer needed. | ||
Practitioner Guidance
What to prioritise: Treat passkeys as the default primary authentication method for users who can support them, but keep a separate policy for recovery, admin elevation, and legacy exceptions. The control decision should be driven by the risk of the action, not by the assumption that every login deserves the same level of friction.
Decision rule: If the question is how to remove password dependence, passkeys are the strategic choice; if the question is how to add extra assurance to a sign-in or step-up event, MFA still matters. Do not use MFA as a reason to delay passkey adoption, and do not use passkeys as a reason to weaken recovery governance.
What to verify: Confirm that fallback paths are at least as well governed as the passkey flow itself. The real test is whether users can still be impersonated through recovery, help desk processes, or privileged exceptions after the primary login is upgraded.
Practitioner takeaway: The strongest modern access strategy is not “passkeys versus MFA,” but a layered design that removes reusable secrets where possible and reserves additional proof for the places where compromise would matter most.
Related resources from NHI Mgmt Group
- What is the difference between passkeys and WebAuthn in modern authentication?
- What is the difference between remote agent authorization and ordinary API access for authentication systems?
- What is the difference between certificate-based authentication and federated identity provider based access?
- What is the difference between authorization and authentication in modern application security?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 10, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
