What is excludeCredentials in WebAuthn?

excludeCredentials is an essential attribute of WebAuthn's PublicKeyCredentialCreationOptions object. This option is used by Relying Parties (RPs) to prevent the creation of multiple credentials for the same account on a single authenticator. It functions by listing credentials that are already registered and should not be re-created.

The key elements of excludeCredentials include:

• Limiting Credential Registration: Prevents redundant credential registration on the same authenticator.
• Credential Enumeration: A sequence of PublicKeyCredentialDescriptor objects representing credentials that are already registered.
• Enhancing Security and User Experience: Avoids confusion and security risks associated with multiple registrations of the same account on a single device.

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excludeCredentials plays a pivotal role in maintaining the integrity of the registration process in WebAuthn. By specifying credentials that should not be recreated, it not only enhances security but also improves the user experience by preventing unnecessary credential duplications.

• Usage in Authentication Flow: During the registration process, excludeCredentials informs the authenticator about existing credentials, directing it to avoid re-creating these credentials.
• Privacy Considerations: Helps in protecting user privacy by not leaking information about the availability of certain credentials.

Since excludeCredentials is part of the PublicKeyCredentialCreationOptions object, you can read more about it in its article.

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excludeCredentials in WebAuthn is used to limit the creation of duplicate credentials for the same account on a single authenticator.

It prevents the registration of multiple credentials for the same account on one device, reducing confusion and potential security risks.

Proper implementation of excludeCredentials can prevent information leaks that could allow identification of specific user credentials.