Overview#
WebAuthn Authenticator Model The
Web Authentication API (
WebAuthN) implies a specific
ABSTRACT functional model for a
WebAuthn Authenticator.For
WebAuthn Authenticator, this model defines the logical operations that they
MUST support, and the
data formats that they expose to the
WebAuthn Client and the
WebAuthn Relying Party. However, it does not define the details of how
authenticators communicate with the
Client Device, unless they are necessary for interoperability with
WebAuthn Relying Party. For instance, this
ABSTRACT model does not define
WebAuthn Authenticator Model does define error behavior in terms of the needs of the WebAuthn Client. Therefore, specific error codes are mentioned as a means of showing which error conditions MUST be distinguishable (or not) from each other in order to enable a compliant and secure client implementation.
WebAuthn Authenticator Model, FIDO-CTAP and CTAP2#
FIDO-CTAP is an
example of a concrete
Implementation of this model, but it is one in which there are differences in the
data it returns and those expected by the
Web Authentication API's
algorithms.
CTAP2 response messages are Concise Binary Object Representation (CBOR) maps constructed using integer keys rather than the string keys defined in this specification for the same objects. The client is expected to perform any needed transformations on such data. The FIDO-CTAP specification details the mapping between CTAP2 integer keys and WebAuthN string keys.
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