Passkey

What is a passkey?

A passkey is a passwordless authentication credential based on public key cryptography. Instead of storing a shared secret like a password, a passkey consists of a private key stored securely on a user’s device and a corresponding public key stored by the service.

When a user authenticates, the device proves possession of the private key using a cryptographic challenge. This process eliminates the need to transmit or store passwords, reducing exposure to phishing and credential theft.

How does passkey authentication work?

Passkey authentication relies on asymmetric cryptography and device-bound credentials:

1. A user registers with a service, generating a public/private key pair.
2. The public key is stored by the service; the private key remains on the user’s device.
3. During login, the service sends a challenge.
4. The device signs the challenge using the private key.
5. The service verifies the signature using the public key.

Authentication is typically unlocked with biometrics or a device PIN, combining strong cryptography with user-friendly access control.

Passkey vs password: what’s the difference?

Passkeys and passwords represent fundamentally different authentication models:

• Passwords: Shared secrets that can be reused, guessed, or stolen
• Passkeys: Unique cryptographic credentials that never leave the device

Key differences:

• Passkeys are resistant to phishing; passwords are not
• Passkeys eliminate credential reuse across systems
• Passkeys rely on device security and user presence
• Passwords depend on user behavior and policy enforcement

This shift removes the primary attack vector attackers rely on: compromised credentials.

Are passkeys secure?

Passkeys significantly improve security by removing shared secrets and relying on asymmetric cryptography for authentication. Instead of transmitting credentials over the network, authentication is performed through a challenge-response mechanism in which the private key never leaves the user’s device. This design eliminates entire classes of attacks that depend on credential interception or reuse.

Because each passkey is bound to a specific domain and cryptographic key pair, phishing attacks are ineffective. Even if a user is tricked into visiting a malicious site, the authenticator will not produce a valid signature for a different origin. Similarly, credential stuffing and password spraying attacks fail because there is no reusable secret to replay across services or accounts. Replay attacks are also mitigated since each authentication request includes a unique, time-bound challenge that cannot be reused.

However, passkey security is not absolute and depends on several underlying controls. The integrity of the endpoint is critical, since malware or a compromised device could potentially access or misuse the private key through the authenticator interface. Secure key storage, typically enforced through hardware-backed modules such as TPMs or secure enclaves, is essential to prevent key extraction. In addition, identity lifecycle management remains a core requirement, including provisioning, recovery, revocation, and device synchronization, especially in enterprise environments where users operate across multiple devices and identity providers.

Use cases

• Passwordless authentication for workforce access
• Secure login for SaaS and cloud applications
• Consumer authentication for web and mobile apps
• Reducing helpdesk workload from password resets
• Strengthening zero trust and identity-first security strategies

How Netwrix can help

Passkeys are gaining adoption, but passwords remain widely used across most environments.

Organizations still rely on passwords for service accounts, legacy applications, hybrid identity setups, and offline systems. These areas often present the highest risk because they are harder to modernize and easier for attackers to exploit.

That is why strong password policy enforcement remains essential.

Netwrix Password Policy Enforcer complements passkey adoption by securing the parts of your environment where passwords are still required.

With Netwrix, you can:

• Block weak and compromised passwords before they are used
• Enforce granular policies across hybrid Active Directory and Entra ID environments
• Reduce exposure to password spraying and credential-based attacks
• Provide real-time feedback so users create compliant passwords on the first attempt
• Align with standards such as NIST 800-63B and PCI DSS

Security is not about eliminating passwords everywhere.

It is about controlling them wherever they still exist.