Passkeys reduce phishing exposure, but they do not replace identity governance around enrollment, recovery, and device re-binding. SMS OTP is weaker at the channel level, while passkeys can still leave blind spots if the surrounding process is abused. The right comparison is lifecycle assurance, not just factor strength.
Passkeys and SMS OTP are not comparable on strength alone
Teams should compare them as authentication systems with different failure surfaces, not as “modern versus legacy” factors. Passkeys materially improve phishing resistance because the credential is bound to the relying party, while sms otp remains exposed to relay, number porting, and social engineering. The more important question is whether the surrounding enrollment, recovery, and re-binding process is controlled well enough to preserve that advantage.
That is why passkeys can be stronger and still fail operationally if recovery is weak. A consumer IAM design has to account for device replacement, lost phones, account recovery support, and re-enrollment rules, because those are the points where attackers often stop being blocked by the factor itself and start targeting the workflow.
For teams comparing the two, the practical unit of analysis is the full lifecycle: sign-up, first binding, recovery, step-up, device change, and revocation. A passkey program that assumes “phishing-resistant equals safe” can create blind spots, while an SMS OTP program that treats delivery as trust can overstate assurance even when the user experience looks familiar and low-friction.
Where passkeys are better, and where SMS OTP still matters
Passkeys are stronger when the main concern is remote phishing, credential replay, or reused secrets. Because the private key stays on the user’s device and the authentication ceremony is origin-bound, the classic “enter a code into a fake login page” attack path is sharply reduced. The protection is real, but it is not complete unless enrollment and recovery also resist takeover.
SMS OTP is weaker because the channel can be intercepted, redirected, or coerced. It may still be acceptable as a fallback in some consumer environments where adoption constraints are real, but it should be treated as a lower-assurance factor with known attack paths, not as an equivalent alternative to phishing-resistant authentication. In practice, teams should decide whether SMS is temporary migration support or a permanent exception path.
The comparison also changes by population. For a consumer app with broad device diversity, passkeys can improve both security and usability, but they introduce dependency on device ecosystems, sync behavior, and support processes. If those dependencies are not well understood, the organization may replace one weak factor with a stronger factor wrapped in a weaker recovery model.
What consumer IAM teams should compare before choosing
Teams should compare three things first: phishing resistance, recovery assurance, and re-binding risk. Phishing resistance answers how well the factor resists credential theft. Recovery assurance asks whether an attacker can walk through support, email, or social channels to regain access after device loss. Re-binding risk asks what happens when a new device, new number, or new authenticator is attached to the account.
That comparison is usually more useful than a generic “MFA strength” score. In consumer IAM, the most damaging failures often happen when the identity is recovered through weaker channels than the primary sign-in method. Passwordless and Passkeys Guide is a useful reference for the sign-in and recovery mechanics teams need to keep aligned.
Teams should also decide whether to preserve SMS OTP only as a fallback with explicit controls, or to phase it out as passkey adoption rises. If the product allows both, the weaker path often becomes the attacker’s preferred path, especially when account recovery, SIM swap, or support-assisted re-enrollment is easier than the primary authentication ceremony.
Risk and Threat Considerations
Consumer authentication failures usually happen at the edges, not in the factor itself. Passkeys can lower phishing risk substantially, but they still depend on secure enrollment, device trust, and recovery controls. SMS OTP creates a broader attack surface because adversaries can target the mobile number, the carrier, or the user’s support interactions instead of attacking the login factor directly.
Failure mechanism: Attackers abuse weaker recovery or re-binding workflows to bypass a strong sign-in factor, or they intercept SMS delivery through SIM swap, port-out fraud, forwarding abuse, or phishing relay.
Impact: Account takeover can occur even when the preferred authentication factor is strong, which means the effective assurance level is set by the weakest recovery path, not the strongest login method.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-63, NIST SP 800-53 Rev 5 and OWASP ASVS set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-63 | Digital Identity Guidelines | Passkeys, OTP, and authenticator assurance are core digital identity concerns. |
| Recommendation — Apply the assurance guidance to compare authenticators and recovery paths by required confidence level. | ||
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | SMS OTP and passkeys both depend on credential lifecycle and authenticator handling. |
| IA-2 — Identification and Authentication (Organizational Users) | The comparison turns on how users are authenticated and what assurance that authentication provides. | |
| Recommendation — Enforce authenticator lifecycle controls for issuance, rotation, revocation, and recovery. Use strong authentication requirements that match the account risk and recovery exposure. | ||
| OWASP ASVS | V6 — Authentication | Consumer IAM sign-in strength and phishing resistance are authentication concerns. |
| V7 — Session Management | Passkey and OTP choices affect session establishment, re-authentication, and account recovery flows. | |
| Recommendation — Verify authentication flows resist phishing, replay, and weak fallback paths. Validate session and step-up behavior so recovery does not weaken authenticated access. | ||
Practitioner Guidance
What to verify: Confirm which channels can enroll a new passkey, reset an account, or bind a new device, and treat any channel that can do all three as part of the authentication attack surface. If SMS remains enabled, verify whether it is restricted to low-risk recovery only or still accepted for primary access.
Decision rule: If the user can regain access through support or email without strong step-up controls, the account is not truly passkey-secured. In that case, prioritize recovery hardening before expanding passkey rollout.
What good looks like: The user can add, lose, replace, and revoke authenticators without creating a support path that is easier to abuse than the original login. The best consumer IAM designs make account recovery observable, rate-limited, and resistant to social engineering.
Practitioner takeaway: Compare passkeys and SMS OTP by the assurance of the full identity lifecycle, because the authentication factor only matters if enrollment, recovery, and device re-binding are at least as strong as sign-in.
Related resources from NHI Mgmt Group
- How should consumer IAM teams reduce reliance on SMS OTP without hurting conversion?
- What should IAM teams do if regulators reject SMS OTP for authentication?
- What do IAM teams get wrong about consumer passkeys in the workplace?
- How should IAM teams compare passkeys with traditional password-based sign-in?