Privacy in Passkey Authentication: What You Really Need to Know

Security and convenience typically take center stage in discussions about passkeys, the phishing-resistant, passwordless authentication option bolstered by biometric methods. Yet often neglected in these conversations is user privacy, leaving room for misconceptions. This article addresses common privacy misunderstandings, explains how passkeys protect user data, and outlines compliance with leading privacy regulations.

Read the full article here

How Passkey Authentication Works from a Privacy Perspective

Passkeys replace traditional passwords using cryptographic keys. When a passkey is created during initial registration, your device generates a unique public-private key pair. The public key, stored on the website or service you registered with, is separate from your private key, which never leaves your secure device.

When you log in, the website sends a challenge request to your device, requiring your private key for signing. To access the private key, you provide local biometric authentication — Face ID, Touch ID, or fingerprint readers ensure you alone can unlock it. It’s crucial here: biometric data itself is never sent over the internet or shared with the site. It’s strictly device-local.

Privacy by Design in Passkey Authentication

Preventing Cross-Site Tracking

Unlike single sign-on methods (SAML or OAuth-based logins like Google/Facebook), passkeys generate separate, unique cryptographic credentials for each website or app. This architecture ensures that organizations cannot track your online activity across multiple platforms using your login credentials.

End-to-End Encryption (E2EE)

When passkeys are synced and backed up across multiple devices, they leverage end-to-end encryption. Even the cloud provider itself cannot access or interpret your passkeys, preserving your data’s confidentiality.

User Control and Transparency

Passkeys live securely within your hardware security module (HSM) or a similarly secure local enclave and are encrypted during transfer and storage. Users retain full ownership and transportability of their authentication data, always knowing how and where their credentials are kept.

Key Presence Protection

Servers remain unaware of whether a passkey actually resides on a user’s device unless explicitly triggered by an authentication attempt, securing users against unauthorized probing or malicious activity.

Common User Misunderstandings About Passkeys & Biometrics

“Is my biometric data sent to the website when logging in with passkeys?”

No. Your biometric information remains securely on device hardware and is only used to authorize access to your private key. Biometrics do not leave your trusted device.

“Can companies track me across different websites using passkeys?”

No. Each passkey is uniquely created per site. Without shared identifiers, cross-site tracking isn’t possible. Passkeys offer far greater privacy than federated login methods.

“If I lose my device, will I lose access to all my accounts?”

Your accounts remain protected. Passkeys typically provide secure, cloud-based backups with end-to-end encryption, allowing recovery on a new, authenticated device.

Some further common questions — such as employer access to personal passkeys or details about dedicated hardware storage encryption — are discussed in greater depth on our full blog post.

Regulatory Compliance: GDPR, PSD2, CCPA and NIST Guidelines

The robust privacy characteristics of passkeys inherently align with leading privacy-focused legislation:

  • GDPR: Supports data minimization and security requirements through secure local biometrics, minimal user information disclosure, and secure data transmission.
  • PSD2: Meets stringent multifactor-authentication requirements, delivering strong customer authentication without sacrificing user privacy.
  • NIST Guidelines: Recognizes passkeys as secure, phishing-resistant authentication, fully compliant with security assurance levels suggested by NIST.
  • CCPA: Passkeys reinforce security and data minimization principles in line with the objectives of California’s privacy act.

For more details on specific compliance points, including future developments toward data portability, consult the full article.

Conclusion

Many widespread privacy concerns about passkeys are based on misconceptions or confusion with older authentication methods. With unique keys per website, strict biometric data protection, no cross-site tracking, and full compliance with leading data protection regulations, passkeys clearly provide significant privacy benefits compared to passwords.