How do passkeys change the risk model compared with passwords and one-time codes?

How passkeys change the login threat model

Passkeys replace the user-readable secret with a cryptographic credential bound to the legitimate origin, so the challenge is no longer “did the user spot the fake?” but “did the authenticator see the right relying party?” That shifts the failure point from human judgment to protocol and device trust, which is why phishing-resistant sign-in is the core security gain. See the broader rollout and recovery implications in the Passwordless and Passkeys Guide and the NIST SP 800-63 Digital Identity Guidelines.

Compared with passwords, passkeys remove reusable shared secrets from the user path, so credential stuffing and password reuse stop being the default attack story. Compared with one-time codes, they also avoid code entry into a page that can relay or capture the value in real time. The practical effect is that the common attacker objective changes from stealing a secret the user can type to trying to compromise the device, the authenticator, or the registration and recovery path.

That does not make sign-in “solved.” The remaining risk concentrates in enrollment, device loss, cloud sync, account recovery, and any channel that can re-bind a new authenticator. In other words, passkeys narrow the attack surface at login, but they move more of the security burden to lifecycle governance and recovery design, where weaker processes can reintroduce the same account-takeover outcome through a different door.

Why passkeys are stronger than passwords and OTPs against phishing

Passwords can be reused, guessed, reset, or harvested by deceptive login pages. One-time codes are better than passwords, but they still depend on the user delivering a code to the right site at the right moment. Passkeys instead use origin-bound public-key cryptography, so a fake login page cannot simply collect a reusable secret and replay it elsewhere.

This changes the economics of phishing. An attacker can still imitate a brand and lure a user, but the spoofed page cannot complete the authentication ceremony against the legitimate origin in the way password and OTP phishing often can. That means the attacker must escalate to more expensive methods such as endpoint compromise, session theft, adversary-in-the-middle setup around enrollment, or abuse of a separate recovery channel.

For practitioners, the most important distinction is that OTPs reduce static-secret risk but not real-time relay risk. Passkeys are designed to break that relay pattern by tying the ceremony to the authentic origin and an approved authenticator, which makes them materially more resistant to the sort of deceptive login flows that defeat people under pressure.

What residual risks still matter after migration

Passkeys reduce phishing exposure, but they introduce a different set of operational assumptions. If an organisation allows broad sync across devices, weak recovery flows, or help-desk-driven re-enrollment, the security posture can drift back toward account takeover risk even though the front-end login is stronger. The risk is less about password theft and more about control of the device ecosystem and the account recovery path.

Attackers also adapt. They may target the user’s existing session, exploit a compromised device, abuse social engineering in recovery, or go after environments where legacy fallbacks still exist. This is why passkeys should be treated as a strong control against credential phishing, not as a complete identity assurance strategy on their own.

Risk and Threat Considerations

Passkeys materially reduce the chance that a fake login page can harvest reusable credentials, but they also concentrate value in the authenticator, the device, and the recovery workflow. If those surrounding controls are weak, attackers can bypass the stronger login ceremony by attacking registration, recovery, or an already-established session instead.

Failure mechanism: A phishing site or malicious actor cannot complete the passkey challenge against the wrong origin, so it shifts to stealing a session, compromising a device, or abusing account recovery to bind a new authenticator.

Impact: The organisation keeps the same account-takeover exposure, but the attacker path becomes less obvious and may be harder to detect because the initial login no longer looks like a simple password or OTP theft event.

Practitioner Guidance

What to verify: Treat recovery and re-enrollment as part of the control, not an exception to it. If a user can add a new passkey through a weak recovery flow, the phishing-resistance benefit of the primary sign-in path is undermined.

What to measure: Track how many authentication-related incidents move from login compromise to recovery abuse, help-desk resets, or session theft. That tells you whether passkeys are reducing the right risk or just relocating it.

Common mistake: Keeping passwords or SMS codes as an equally easy fallback defeats the point. The real control is not “passkeys available,” it is “passkeys are the preferred, strongly governed path and legacy alternatives are tightly limited.”

Practitioner takeaway: Passkeys lower phishing success by removing the secret the user can be tricked into typing, but the security win only holds if recovery, device trust, and fallback authentication are governed to the same standard as the login itself.

Related resources from NHI Mgmt Group

• Why do passkeys reduce replay risk more effectively than passwords plus one-time codes?
• How should security teams reduce phishing, vishing, and smishing risk without relying only on passwords or one-time codes?
• Why do time-based one-time passwords reduce the risk of account compromise better than reusable login codes?
• Why do magic links and one-time passwords reduce risk compared with traditional passwords?