Passkeys remove the shared-secret problem that makes passwords and SMS codes easy to phish or intercept. They still require disciplined enrolment and recovery, but they shift assurance toward possession of a private key plus user verification, which is materially stronger than reusable credentials.
Why This Matters for Security Teams
Passkeys are not just a better login experience. They change the assurance model by replacing reusable shared secrets with cryptographic proof bound to a device and user verification. That matters because passwords and SMS codes are still routinely defeated by phishing, replay, SIM swap, and help desk abuse. NIST’s digital identity guidance treats authenticator strength and resistance to interception as core assurance factors in NIST SP 800-63 Digital Identity Guidelines.
For NHI Management Group, the practical lesson is that stronger human identity assurance reduces one major source of credential theft, but it does not solve Non-Human Identity risk on its own. The same organisations that still struggle with secrets sprawl, excessive privilege, and poor rotation in Ultimate Guide to NHIs often assume one stronger factor fixes the full identity stack. It does not.
Passkeys also align better with modern identity proofing than SMS because there is no shared code to intercept in transit, and no long-lived password database to steal and reuse. In practice, many security teams encounter account takeover only after phishing-resistant controls were postponed in favour of legacy MFA that looked sufficient on paper.
How It Works in Practice
A passkey is typically a public-private key pair stored in a device or synced credential store. During authentication, the service challenges the user, and the private key signs that challenge only after local user verification such as biometric unlock or PIN entry. The server never receives the private key, so there is no secret for an attacker to replay. That design is fundamentally different from passwords and SMS one-time codes, both of which can be captured and reused if the user is tricked or the channel is compromised.
In identity assurance terms, passkeys usually provide stronger phishing resistance than SMS and stronger replay resistance than passwords. Current guidance from NIST SP 800-63 Digital Identity Guidelines and the EU digital identity framework in eIDAS 2.0 both point toward stronger authenticators and reduced reliance on interceptable factors.
For practitioners, the main implementation questions are enrolment, recovery, and step-up policy:
- Use passkeys as the primary sign-in method where device-bound or synced credentials are acceptable.
- Require strong recovery paths, because recovery is often the weakest link after password removal.
- Keep SMS only as a transitional fallback, not as the primary assurance mechanism.
- Apply step-up controls for high-risk actions instead of assuming first-factor login proves everything.
For NHI governance teams, this same logic is why secrets management, rotation, and offboarding remain essential for APIs and service accounts, even when human users move to passkeys. The risk profile of service credentials is described in 52 NHI Breaches Analysis and the broader credential exposure patterns in the Ultimate Guide to NHIs. These controls tend to break down when recovery workflows are weak, because attackers shift from login interception to account recovery abuse.
Common Variations and Edge Cases
Tighter authentication often increases operational overhead, requiring organisations to balance stronger assurance against user support, device lifecycle complexity, and recovery risk. Passkeys are not a universal cure, and best practice is still evolving around cross-device sync, enterprise attestation, and regulated environments.
One important distinction is whether the passkey is device-bound or synchronised across a user’s cloud account. Synced passkeys improve usability and recovery, but some environments prefer device-bound authenticators for higher control. There is no universal standard for every assurance tier, so policy should reflect the sensitivity of the application and the organisation’s threat model.
SMS codes remain common for account recovery and low-risk journeys, but they should not be treated as equivalent to phishing-resistant authentication. They are vulnerable to SIM swap, SS7 interception, and social engineering against telecom support. Passwords can still be appropriate in legacy systems, but only when paired with compensating controls and a clear migration plan.
For high-assurance use cases, passkeys should be paired with risk-based authentication, recovery controls, and strong identity proofing. That is especially important where account takeover has downstream effects on NHI administration, API key issuance, or privileged access workflows. In practice, organisations usually discover the limits of SMS after a takeover, not during design reviews.
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 and CSA MAESTRO address the attack and risk surface, while NIST SP 800-63, NIST CSF 2.0 and NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-63 | Defines authenticator strength and phishing resistance for identity assurance. | |
| NIST CSF 2.0 | PR.AA-1 | Identity proofing and authentication map directly to access assurance. |
| OWASP Non-Human Identity Top 10 | NHI-01 | Credential exposure patterns affect human and non-human identity assurance. |
| NIST AI RMF | GOVERN | Governance is needed when authentication changes affect risk and recovery. |
| CSA MAESTRO | ID-01 | Identity-centric security design supports stronger authentication flows. |
Use phishing-resistant authenticators and stronger recovery controls for higher assurance transactions.
