Passkeys and Digital Credentials: A Practical Guide to Modern Authentication

Why Authentication Needs a Complete Overhaul

Imagine this: a user visits your website and their very first interaction is filling out a lengthy, high-friction registration form. At that moment, many users will simply bounce — and never come back. Those who do stick around are only the highly motivated ones, but regardless, the first impression has already been damaged.

And that's just the tip of the iceberg. Beyond registration friction, users face phishing attacks, identity theft, and a host of other security threats. The root cause often comes down to developers still relying on outdated, legacy authentication technologies.

In this session from Google I/O Connect, the team goes beyond listing new technologies and instead takes a broader view — helping developers understand authentication as a complete systems engineering problem.

The User Account Lifecycle: The Right Way to Think About Authentication

The key to understanding modern authentication is stepping back from individual technologies and seeing the complete user account lifecycle. Only by placing each technology in the right stage of that lifecycle can you truly evaluate whether it's the right fit.

The lifecycle breaks down into four core phases:

1. Account Creation

This is where users establish a relationship with your service — and it's also where drop-off rates are highest. Traditional username + password registration flows carry enormous friction. Modern approaches emphasize getting users through account setup in as few steps as possible.

2. Attribute Verification

In certain scenarios, you need to verify specific user attributes — such as an email address, phone number, or even age and identity information. This phase has historically relied on cumbersome SMS codes or email confirmations, but more standardized, secure protocols are now available as replacements.

3. Subsequent Sign-in

First-time registration is just the beginning — every return visit matters just as much. Repeatedly prompting for passwords or requiring frequent two-factor authentication steadily erodes user patience.

4. Account Recovery

When users lose their device or forget their credentials, helping them regain access safely is one of the most overlooked yet critically important phases. A poorly designed recovery flow often becomes the weakest link in the entire security chain.

Account recovery is the "soft underbelly" of a security system because it is fundamentally an identity reconstruction process — users must prove who they are after losing their original credentials. Traditional recovery methods (security questions, backup email addresses) can often be bypassed through social engineering attacks, and several high-profile account hijacking incidents have been traced back to exactly this. Modern best practices include: setting up multiple recovery keys in advance, leveraging Passkeys' cross-device sync capabilities (such as iCloud Keychain or Google Password Manager's cloud sync) as a built-in recovery mechanism, and introducing Trusted Contacts — incorporating social networks into the recovery flow to strike a better balance between usability and security.

The Modern Authentication Toolkit

For each phase of the lifecycle, there are corresponding modern technologies that can significantly improve both user experience and security. Here are the key solutions worth understanding:

Passkeys

Passkeys are the most widely recognized alternative to passwords. Built on public-key cryptography, they are inherently phishing-resistant — users don't need to remember any password and simply authenticate using their device's biometrics (fingerprint or face recognition). Passkeys improve both the account creation and subsequent sign-in phases.

From a technical standpoint, Passkeys are based on the FIDO2/WebAuthn standard and use an asymmetric encryption model. During registration, the device generates a key pair locally: the private key never leaves the user's device (stored in a secure enclave or TPM chip), while the public key is uploaded to the server. At sign-in, the server sends a random challenge, the device signs it with the private key and returns it, and the server verifies the signature using the public key. Because the private key is never transmitted, even if a server database is compromised, attackers cannot exploit the leaked public keys to forge identities — fundamentally eliminating the risk of password database breaches, a problem that traditional password schemes struggle to fully solve regardless of salting or encryption.

Email Verification Protocol

For the attribute verification phase, a standardized email verification protocol makes the verification flow smoother and more reliable, reducing the back-and-forth between confirmation emails and copying verification codes.

Digital Credentials API

The Digital Credentials API allows users to securely present verified identity information (such as a digital ID or driver's license) to websites. It's especially valuable in scenarios requiring strong attribute verification, protecting privacy while increasing trust.

This API is built on the W3C Verifiable Credentials (VC) standard. Verifiable Credentials are digitally signed, cryptographically verifiable identity assertions issued by authoritative bodies (such as governments or banks) and stored in a user's digital wallet (like a phone's wallet app). When a website requests verification, users can selectively disclose only the required attributes — for example, proving "age is over 18" without submitting a full ID number — embodying the principle of minimal disclosure. This is particularly valuable in regulated industries like finance and healthcare that require KYC (Know Your Customer) checks, while avoiding the privacy risks of centralized identity databases.

FedCM (Federated Credential Management)

FedCM provides a more privacy-respecting, browser-native mechanism for federated sign-in (such as "Sign in with Google"). As third-party cookies phase out, it is essential infrastructure for maintaining a smooth federated login experience.

Understanding why FedCM is necessary requires context about the broader third-party cookie deprecation. For years, identity providers like Google and Facebook used third-party cookies to detect cross-site login states, enabling seamless one-tap sign-in. But as Chrome, Safari, and other browsers have progressively restricted or blocked third-party cookies, traditional federated login mechanisms face the risk of breaking down. FedCM's solution is to make the browser itself the intermediary: communication between identity providers and relying parties no longer depends on cookie tracking. User identity information flows through the browser's oversight in a more transparent, controllable manner — while preserving the smooth one-tap sign-in experience, achieving both privacy protection and user convenience.

Real-World Impact: The Numbers Speak

Technology upgrades bring more than conceptual improvements — they deliver concrete business metric gains. Two key data points are worth highlighting:

• 2× faster sign-in: Adopting modern solutions like Passkeys doubles the speed at which users complete the sign-in flow;
• 4× higher success rate: Sign-in success rates are four times higher than traditional methods, meaning far fewer users are lost due to authentication failures.

The logic is straightforward: less friction plus stronger security equals less user drop-off and naturally higher conversion rates. The failure of traditional password schemes isn't just about security vulnerabilities — it's also the ongoing erosion of user experience. Forgotten passwords, typos, locked accounts: these scenarios chip away at user trust every single day. Modern authentication technologies eliminate these friction points at their root.

Action Recommendations for Developers

When designing or refactoring an authentication system, the core objective should be crystal clear:

Gradually phase out brittle, high-friction sign-in methods and enable simpler, friendlier, and more secure modern alternatives.

Specifically:

• Don't treat authentication as a one-time technology decision — plan it in phases aligned with the account lifecycle;
• Prioritize introducing Passkeys as a replacement or complement to passwords, leveraging the cross-platform compatibility of the FIDO2 standard to reduce migration costs;
• Use standardized protocols and the Digital Credentials API for attribute verification scenarios, protecting user privacy through minimal disclosure;
• Use FedCM to address the federated login challenges brought on by third-party cookie deprecation — get ahead of it rather than reacting after the fact;
• Give account recovery the same design priority as everything else, and prevent it from becoming the weak link in your entire security architecture.

Authentication is at a critical inflection point. Passwords are no longer the default — they are a "legacy technology" that needs to be gradually retired. Whoever can deliver a passwordless, phishing-resistant, low-friction authentication experience to users first will win user trust from the very first impression.

Key Takeaways