Hey, let’s be honest: passwords are over. SMS‑codes, pushpopups, totp tokens, great in theory, weak in real‑life fights. bad guys surf that weakness like it’s a goldmine. phishing got too smart, MFA fatigue is real, and attackers no longer brute-force, they social-engineer the hell out of u.
that’s where FIDO2 crashes in like a hero, crypto-based, phishing‑proof, bound to the site you’re actually on. no more fake‑site tricks or fatigue taps. it doesn’t ask if u trust the site, it knows.
for the FIDO2 protocol stack, see the official spec here: https://fidoalliance.org/specs/fido-v2.1-id-20210602/
what sucks about old-school MFA?
MFA is not broken, but it sure isn’t bulletproof. SMS is still used by banks (😬), but it’s as insecure as cardboard armor, SIM swapping, SS7 hijacks, cloned phones.
TOTP apps? better, sure. but still vulnerable to phishing proxies. modern kits like Evilginx2 clone login portals, steal the code in real time, pass it upstream.
Push notifications? welcome to alert fatigue. users tap YES without looking, even at 3:14 a.m. attackers love this. they flood users until one careless click gives them the gold.
according to Verizon’s 2023 DBIR, 74% of breaches involved the human element. MFA alone ain’t enough: https://www.verizon.com/business/resources/reports/dbir/
FIDO2 101, crypto-shirt for your identity
FIDO2 is not a new auth flow, it’s a redesign. it says: no shared secrets, no SMS roulette, no “I hope this code’s legit.”
what it gives u:
- a private key per user, per site. stored in hardware or secure enclave
- a public key stored on server, used only to validate your auth
- built-in origin binding, won’t sign outside the legit domain
- no shared secrets, no symmetric replay risk
- works via WebAuthn (browser API) and CTAP2 (client to authenticator)
examples of devices?
- YubiKeys, Titan Security Keys, Windows Hello, Apple Face ID
- smartphones with biometric unlock + hardware keystore (Android/iOS)
actual protocol flow:
- client (browser) challenges via WebAuthn
- token signs challenge using private key bound to site origin
- server checks that sig against registered public key
- access granted ONLY if everything checks, including origin
and it’s all transparent to users. just tap, or scan face, or fingerprint. no codes, no thinking, no copying digits off your phone while typing.
technical deep dive from Microsoft: https://techcommunity.microsoft.com/t5/security-compliance-and-identity/how-fido2-and-webauthn-work-in-microsoft-entra-id/ba-p/3899847
passkeys, passwords’ much cooler cousin
Google, Apple, Microsoft now fully support passkeys. it’s FIDO2 underneath, but with sugar on top:
- your device syncs keys across your cloud (iCloud, Google, MSFT)
- you log in just like Face ID or Hello, PIN, face, whatever
- device figures out the rest
it makes passwordless mass-adoptable.
best part? passkeys are unique per site, phishing resistant, and stored locally. no central vault, no one to hack in bulk. attackers have to steal YOUR exact device AND unlock it.
and even then? they can’t use your keys on a different domain. they’re bound by origin.
see Microsoft’s implementation guidance here: https://learn.microsoft.com/en-us/azure/active-directory/authentication/concept-authentication-passwordless
real-world math and nerd juice
Microsoft, Apple, NIST, and FIDO Alliance all tested FIDO2-based systems under stress. highlights:
- 50x fewer phishing-successful logins in controlled studies
- >90% reduction in helpdesk reset requests in large org rollouts
- threshold cryptography now used in hardware-backed passkeys
- attestation chains prevent rogue key registration from compromised tokens
and for the math lovers:
- challenge is a SHA-256 hash, signed via ECDSA (P-256)
- server checks: Verify(PUBKEY, challenge, signature) == true
- origin must match: enforced via browser and token firmware
- some advanced keys now use elliptic curve pairings for stronger binding
also check NIST’s 800-63B standards for digital identity: https://pages.nist.gov/800-63-3/sp800-63b.html
rollout at scale, Azure, Entra ID, and more
Microsoft’s Azure AD (now Entra ID) supports FIDO2 in hybrid mode:
- register keys via Intune policies
- enforce MFA rules with Conditional Access
- combine FIDO2 login with SSO tokens
- block sign-ins if token attestation fails
Windows Hello is a FIDO2 platform authenticator. so if you’re on a Surface device, hello smile + TPM = FIDO2 in action.
even Windows Server 2025 will let u go fully passwordless in hybrid AD setups. FIDO2 logins, kerberos backed, even on RDP!
see Microsoft blog by Alex Weinert: https://techcommunity.microsoft.com/t5/security-compliance-and-identity/why-passwords-are-still-a-problem-and-how-to-fix-it/ba-p/2331886
but wait, still not unicorns and rainbows
FIDO2 is damn good. but there ARE dragons:
- device loss = key loss. so recovery is nontrivial
- legacy apps? they don’t know WebAuthn from a hole in the wall
- token cloning (rare but seen in 2021 on misconfigured keys)
- enterprise SSO chains still rely on fallback passwords 😬
to really go passwordless, u need:
- app support
- identity federation cleanup
- smart policies on token binding, re-registration, and risk detection
expert discussion by Joy Chik (Microsoft VP of Identity): https://www.linkedin.com/pulse/future-passwordless-joy-chik
TL;DR: stop typing codes. plug in crypto.
FIDO2 is the endgame for MFA. it binds u to the site, protects against phishing, removes passwords, and does it with math, not hope.
passkeys make it work for everyone. Azure and Microsoft stack make it scalable.
and it’s fun to use. like, tap-click-done fun.
📎 bonus: try phishing it. seriously. you can’t. unless your attacker’s a time traveler with access to your TPM.
learn more: https://www.microsoft.com/en-us/security/blog/2023/05/09/fido2-passwordless-authentication-guide/ https://www.fidoalliance.org/fido2/ https://webauthn.guide/