Passkeys shift authentication, but implementation still carries risk

At a glance

What this is: This article explains how passkeys work in web applications and shows that the main risk is implementation complexity, not the underlying passwordless model.

Why it matters: IAM and identity teams need to treat passkeys as a full authentication architecture change because registration flows, authenticator handling, and key storage all affect security outcomes.

Context

Passkeys are a passwordless authentication mechanism built on public key infrastructure, where the client creates and stores the private key while the server stores the public key. That architecture changes how identity proofing, registration, and authentication are handled in the browser, on the platform, and on the server.

For IAM teams, the real issue is not whether passkeys are more secure than passwords in principle. The governance question is whether the organisation can implement authenticator selection, key storage, and lifecycle handling without introducing weak registration logic or brittle operational dependencies.

Prove Identity’s analysis is aimed at the implementation layer, where browser support, platform support, and authenticator metadata all shape the actual risk profile. That makes passkeys an identity programme topic, not just an authentication feature toggle.

Key questions

Q: How should teams implement passkeys without creating avoidable authentication complexity?

A: The safest path is to use a supported WebAuthn library or an identity workflow platform rather than hand-coding the ceremony. Passkeys require challenge generation, attestation handling, signature verification, device registration, and secure storage of credential metadata. Teams also need HTTPS, user identification logic, and recovery planning. Treat passkeys as an authentication system, not a single front-end feature.

Q: What makes passkey registration a security control point?

A: Registration is where the organisation binds a new authenticator to an account, so it is the moment to validate device trust, capture metadata, and reject insecure authenticators. If that step is weak, the later authentication flow inherits the bad decision. Teams should therefore treat registration review as part of identity governance, not only development work.

Q: When do passkeys reduce risk, and when do they just add another credential type?

A: Passkeys reduce risk when they replace reusable secrets and are tied to strong phishing-resistant authentication flows. They add little value when they are bolted onto weak recovery, poor prompting, or inconsistent device support, because the identity failure shifts from login to enrolment and support.

Q: How should organisations decide whether to prioritise passkeys over passwords?

A: Organisations should prioritise passkeys when they want stronger authentication with less user friction and a cleaner path toward passwordless access. Passkeys use device based proof of identity instead of shared secrets, which reduces reliance on passwords and can improve privacy. The decision depends on how well teams can integrate them into existing authentication flows.

Technical breakdown

How passkey registration works in web applications

Passkey registration is a two-step ceremony that creates a credential pair and binds it to the server-side account record. The browser passes server-defined policy to the platform authenticator, which generates the key pair locally and returns the public key plus metadata. The server then checks authenticator details, stores the public key, and records what device or mechanism created the credential. The security value depends on validating the authenticator and preserving the metadata that later supports lifecycle decisions.

Practical implication: design registration as a governed control point, not just a UX flow.

Why authenticator selection and platform support matter

Passkeys are only as safe as the authenticator path the server allows. FIDO2 and WebAuthn depend on browser and platform interaction, but the server still has to decide which authenticators are acceptable and whether any are insecure or compromised. Because passkeys live on the underlying device, weak policy on supported authenticators can turn a strong cryptographic model into a weak trust decision. The implementation challenge is therefore selection, not just cryptography.

Practical implication: enforce authenticator policy and reject unsupported or risky device classes.

What server-side key handling changes in the passkey model

In a passkey model, the server no longer stores a reusable password secret, but it still holds public key records, challenge logic, and authenticator metadata. Authentication succeeds only when the server can match the returned challenge to the stored public key and verify that the authenticator completed the signing step correctly. That means the server design must preserve integrity across registration, challenge generation, and credential lookup. The attack surface shifts from password theft to implementation errors and trust handling.

Practical implication: secure the public-key registry, challenge flow, and metadata store as core authentication assets.

NHI Mgmt Group analysis

Passkeys are not a password replacement, they are an authentication architecture change. The article shows that the security model depends on how browsers, platforms, authenticators, and server-side policy interact. That means teams must evaluate passkeys as a governed identity flow, not a feature layer, because implementation quality determines whether the passwordless promise survives contact with production.

Authenticator governance is the real control boundary. Server-side approval of acceptable authenticators is where insecure devices, compromised metadata, and weak selection logic become operational risk. The article makes clear that cryptography alone does not settle trust, because the organisation still decides which authenticators are allowed to participate. Practitioners should treat authenticator policy as part of access governance, not only application engineering.

Passkey rollout exposes a classic identity lesson: better primitives do not remove governance obligations. Public key infrastructure removes shared secrets from the user journey, but it does not remove the need to manage registration, storage, device trust, and account recovery. That is why passkeys strengthen the authentication layer only when the programme also strengthens lifecycle and control design.

Developer behaviour remains a weak link even when the identity model improves. Prove Identity’s cited statistic that only 44% of developers follow secrets-management best practices is a reminder that implementation discipline often lags security intent. Passkeys reduce password exposure, but they do not compensate for poor handling of credential material, metadata, or backend integration. The practitioner conclusion is to pair passwordless adoption with developer guardrails and review.

From our research library:

• Only 44% of developers are reported to follow security best practices for secrets management, exposing a significant developer behaviour gap, according to the State of Secrets in AppSec.
• eBay's passkey data shows 55-60% of passkey adoption happens on mobile, against around 20% on desktop.
• Read next: Passwordless and Passkeys Guide

What this signals

Passkey adoption will expose weak governance where teams still treat authentication as a client-side feature. The control boundary moves to authenticator policy, credential binding, and server-side trust evaluation, which means identity teams need to own the operating model rather than leaving it entirely to application teams.

The implementation gap is the durable risk, not the cryptographic design. Even with browser support and platform authenticators in place, the programme can fail if teams cannot manage registration rules, recoverability, and metadata hygiene consistently across applications and device types.

Developer behaviour remains a material signal for rollout readiness. Only 44% of developers are reported to follow security best practices for secrets management according to State of Secrets in AppSec, which suggests many organisations will need stronger review and guardrails before passkeys scale safely.

For practitioners

• Define acceptable authenticator policy Specify which authenticators are permitted, which device capabilities are required, and what metadata the server must evaluate before a credential is accepted.
• Protect registration as a trust decision Treat the registration ceremony as the point where a new identity binding is created, with review of authenticator attestation, storage rules, and account ownership.
• Harden server-side public key handling Store public keys, challenge state, and authenticator metadata in controlled services with strict access boundaries and logging around credential creation and validation.
• Plan for multiple authenticators Allow users to register more than one passkey and maintain clear lifecycle handling for add, remove, and recovery events so a single device failure does not lock out the account.

Key takeaways

• Passkeys improve authentication security by removing shared secrets, but the implementation burden moves to registration, authenticator selection, and backend key handling.
• The biggest practical risk is not the cryptography itself but whether teams can govern the new identity flow consistently across browsers, platforms, and recovery paths.
• Organisations should treat passkey adoption as an IAM architecture change and pair rollout with policy, review, and lifecycle controls.

Key terms

• Passkey: A passkey is a passwordless credential based on public key cryptography. A private key stays on the user’s device, while a public key is stored by the service. During login, the device signs a challenge after local unlock, which reduces phishing and eliminates shared secret reuse.
• WebAuthn: WebAuthn is a browser and platform standard for phishing-resistant authentication using public-key cryptography. It binds the authenticator to the origin and signs a challenge instead of sending a reusable code, which makes replay and relay attacks far harder.
• FIDO2: FIDO2 is a passwordless authentication standard that uses public-key cryptography instead of shared secrets. A service stores the public key while the authenticator keeps the private key, allowing users to prove possession without sending reusable credentials over the network.
• Authenticator Metadata: Authenticator metadata is the information returned during registration that describes the device or security module used to create the credential. It helps the server judge whether the authenticator meets policy requirements and whether it should be accepted for future authentication.

Deepen your knowledge

NHI governance, identity lifecycle management, and secrets management are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If you are building or maturing an IAM programme, it is worth exploring.