Passwordless SSO for Web & Mobile Apps

Passwords are the Internet’s oldest liability. They’re easy to phish, hard to manage, and expensive to support. Passwordless SSO (Single Sign-On) replaces fragile shared secrets with phishing-resistant cryptography, giving users one, seamless login across apps while reducing risk and cost.

This guide explains how to roll out passwordless SSO in modern enterprises. We’ll cover passkeys (FIDO2/WebAuthn), when to use SAML SSO vs OpenID Connect (OIDC), how to align with zero-trust login, and how to integrate with your existing IdP (Okta, Microsoft Entra ID/Azure AD, Ping, Auth0, Keycloak). We’ll finish with buyer checklists, pitfalls, and a practical migration plan.

Quick definitions

• Passkeys (FIDO2/WebAuthn): Cryptographic credentials that live on a user’s device (or in a secure, synced vault) and authenticate with biometrics or PIN. Passkeys are tied to the site/app origin and eliminate usernames and passwords. They’re phishing-resistant by design.
• WebAuthn: A W3C standard enabling websites to create and use passkeys via the browser; credentials are created and scoped per relying party (your domain/app).
• SAML 2.0: An XML-based federation standard widely used for enterprise web SSO (browser-centric, great for legacy apps).
• OpenID Connect (OIDC): An identity layer on top of OAuth 2.0, ideal for modern web, SPA, mobile, and API-driven architectures.
• Zero-Trust login: Don’t trust by network location; continuously verify user and device for each request. NIST SP 800-207 defines the principles and patterns.

Why passwordless SSO now?

• Stop phishing at the root. Government guidance recommends phishing-resistant MFA, not SMS or push codes. FIDO/WebAuthn passkeys are a core example.
• Align with zero-trust. Passwordless SSO pairs origin-bound credentials with continuous device/context checks, as outlined by NIST’s Zero Trust Architecture. [
• Enterprise momentum. Major identity platforms now provide first-class passkey support and enforcement policies (e.g., Microsoft Entra ID, Okta).

How passwordless SSO works (high-level flow)

1. User opens the app (web, SPA, or native mobile).
2. The app redirects to your IdP using SAML or OIDC (OIDC is preferred for mobile/SPA).
3. The IdP performs passwordless authentication with passkeys (WebAuthn).
4. The IdP issues a token (SAML assertion or OIDC ID token) back to the app.
5. The app trusts the token and starts the user’s SSO session.

Because WebAuthn credentials are scoped to a relying party’s origin and use public-key cryptography, users authenticate without a password and phishable steps like SMS/OTP disappear.

Web vs. mobile: SAML SSO or OIDC for passwordless?

Short answer: Use OIDC wherever possible, especially for mobile and SPAs. Keep SAML for legacy browser apps.

• Mobile & native apps: IETF RFC 8252 recommends using the system browser with Authorization Code + PKCE, that’s the OIDC sweet spot. Embedded webviews are discouraged for security/usability.
• SPAs: Modern OIDC patterns (Authorization Code + PKCE) fit SPAs; SAML was designed for server-rendered browser SSO and doesn’t have a native profile for SPAs/mobile.
• Enterprise web apps: SAML remains ubiquitous and stable for classic browser SSO. You can still make it passwordless by using passkeys at the IdP and issuing a SAML assertion to the app.

Passwordless SSO comparison table

Sources:

Security model: why passkeys are different

Passkeys ≠ shared secrets. Each user/app pair has a unique key pair. The private key never leaves the device (or secure OS cloud), and the server verifies a challenge with the public key. Result:
Eliminates credential reuse across sites.
Prevents phishing (signatures are bound to the real origin, not a look-alike).
Reduces helpdesk load (no resets/rotations).

UX patterns that actually work

• Instant sign-in: Face ID/Touch ID/Windows Hello instead of typing. (That’s the passkey ceremony.)
• Cross-device sign-in: Scan a QR code to use a passkey stored on another device, great for desktop + phone, or iOS ↔ Android.
• Device-bound vs synced passkeys: Device-bound maximize hardware security; synced increase convenience. Choose per assurance level and app risk.

Architecture patterns for enterprise SSO and zero-trust login

• IdP-centric passkeys: Add WebAuthn at your IdP (Okta/Entra/Ping/Auth0), then keep existing SAML/OIDC trust to apps. This gives passwordless SSO everywhere without touching each app.
• Policy + device signals: Combine passkeys with device posture, network, and risk signals as NIST ZTA recommends (authenticate user and device).
• Web + mobile together: For mobile, follow RFC 8252 (system browser, Authorization Code + PKCE) via your IdP; for web, keep SAML and/or OIDC depending on the app.

IdP integration: you don’t have to rip and replace

• Microsoft Entra ID: Organization-wide enablement and enforcement (Authentication methods, Authentication strengths).
• Okta: Phishing-resistant authenticators (FIDO/WebAuthn, FastPass) and policies to enforce them.
• Ping Identity: WebAuthn/passkey SDKs and journeys for Android/iOS and OIDC flows.
• Auth0: Passkeys and WebAuthn MFA guidance and implementation patterns.

WWPass delivers passwordless SSO with no usernames and no passwords, compatible with your existing SAML/OIDC app catalog, so you can modernize authentication without breaking SSO.

Implementation guide: from pilot to production

1. Pick your primary protocol per app type

   • Mobile/SPA/new services → OIDC (Auth Code + PKCE).
   • Legacy browser apps → SAML (keep, but move auth to passkeys at the IdP).

2. Turn on passkeys in your IdP

   • Enable FIDO2/WebAuthn authenticators and enforce phishing-resistant policy for high-risk apps.

3. Design enrollment & recovery

   • Offer progressive enrollment (invite users to add a passkey after first login).
   • Provide backup options (second device, hardware security key, admin-assisted recovery with strong proofing).
   • Support cross-device sign-in (QR flow).

4. Map assurance to passkey type

   • Device-bound for high assurance; synced for convenience; allow step-up for sensitive actions.

5. Zero-trust policies

   • Evaluate device posture, geo, network, and risk at each auth and token refresh (per NIST ZTA).

6. Developer patterns

   • Use standard OIDC SDKs; mobile follows RFC 8252 (no embedded webviews).
   • For SAML apps, keep the SAML trust but make the IdP passwordless.

7. Phase rollout

   • Start with IT & security staff → pilot departments → company-wide.
   • Track fallback/exception rates and helpdesk metrics to measure ROI. (Operational best practice.)

Practical comparison: Password-based SSO vs Passwordless SSO

Guidance: CISA recommends phishing-resistant MFA; ZTA emphasizes continuous verification.

Buyer’s checklist: copy into your RFP

A. Authentication & security model
Confirm support for WebAuthn/FIDO2 passkeys; list platform and browser coverage. Provide phishing-resistant MFA documentation and enforcement controls.

B. Protocols & app coverage
OIDC (Auth Code + PKCE) for mobile/SPA; SAML for legacy browser apps. Reference RFC 8252 compliance.

C. Device & recovery
Options for device-bound and synced passkeys; cross-device sign-in; backup keys; admin recovery with strong proofing.

D. Zero-trust integration
Ability to assess device posture and apply risk-based policies at login and token refresh (ZTA alignment).

E. IdP & app catalog
Native passkey support at your IdP (Okta/Entra/Ping/Auth0) and compatibility with SAML/OIDC app libraries.

F. Operations
Telemetry on failed/blocked attempts, enrollment rates, and self-service recovery outcomes. (Operational ask.)

Implementation pitfalls (and how to avoid them)

1. Keeping passwords around “just in case.”
   If users can still choose passwords, they will, and attackers will phish them. Enforce passkeys for high-risk apps and remove password paths over time.

2. Using embedded webviews in mobile.
   Violates RFC 8252; use the system browser with Authorization Code + PKCE.

3. Assuming SAML is fine for SPAs/mobile.
   SAML was never built for native/SPA patterns; prefer OIDC there.

4. Under-investing in recovery.
   Plan for lost devices. Offer backup security keys, additional device enrollments, and strong admin recovery procedures. (General best practice.)

5. Skipping device and context checks.
   Zero-trust means continuously verifying user and device, add device posture and risk-based access.

Frequently asked questions

Can we keep SAML and still go passwordless?
Yes. Add passkeys at the IdP and keep your SAML trusts; the IdP authenticates users passwordlessly and sends a SAML assertion to apps.

Do passkeys work on phones and desktops?
Yes. Passkeys are supported across major platforms/browsers and can enable cross-device sign-in (e.g., scan a QR to use a phone-stored passkey on desktop).

Are passkeys really phishing-resistant?
Yes. They use public-key cryptography bound to your application’s origin; there’s nothing to steal/replay. CISA endorses phishing-resistant MFA.

What about mobile SSO?
Follow RFC 8252: system browser + Authorization Code + PKCE via your IdP’s OIDC.

WWPass perspective (and why enterprises choose us)

WWPass delivers passwordless SSO with no usernames, no passwords, no OTPs, a single, strong login for all your SAML and OIDC apps. The WWPass Key experience consolidates identities while preserving your existing IdP and app catalog.

Step-by-step migration plan (90 days)

Phase 1, Prove it (Weeks 1–3)

• Turn on passkeys in your IdP for IT/security pilot groups.
• Enforce phishing-resistant policy on 3–5 internal apps. Track enrollment and helpdesk impact.

Phase 2, Expand (Weeks 4–8)

• Add customer-facing apps (OIDC). Keep SAML for legacy web.
• Introduce cross-device sign-in for common desk/phone mixes.

Phase 3, Standardize (Weeks 9–12)

• Make passkeys the default factor; restrict fallback to break-glass cases.
• Align access policies with NIST ZTA (user + device verification).

Exact language to request in contracts/security addenda

• “Provider supports WebAuthn/FIDO2 passkeys and offers controls to enforce phishing-resistant MFA for designated apps and user groups.”
• “Mobile flows comply with RFC 8252 (system browser + Authorization Code + PKCE); embedded webviews are disabled or blocked.”
• “Provider aligns with NIST SP 800-207 principles and supports device posture signals for zero-trust policy decisions.”

Bottom line

Passwordless SSO with passkeys (FIDO2/WebAuthn) brings phishing-resistant login to every app, OIDC for mobile/SPA and SAML for legacy web, while aligning with zero-trust. The result is stronger security, a smoother UX, and lower operational cost. Ready to modernize your enterprise SSO? WWPass can help you deploy no-password, no-username sign-in across your web and mobile portfolio, without re-platforming your apps.