NAME

     fido_cred_verify, fido_cred_verify_self — verify the attestation signature of a FIDO2
     credential

SYNOPSIS

     #include <fido.h>

     int
     fido_cred_verify(const fido_cred_t *cred);

     int
     fido_cred_verify_self(const fido_cred_t *cred);

DESCRIPTION

     The fido_cred_verify() and fido_cred_verify_self() functions verify whether the attestation
     signature contained in cred matches the attributes of the credential.  Before using
     fido_cred_verify() or fido_cred_verify_self() in a sensitive context, the reader is strongly
     encouraged to make herself familiar with the FIDO2 credential attestation process as defined
     in the Web Authentication (webauthn) standard.

     The fido_cred_verify() function verifies whether the client data hash, relying party ID,
     credential ID, type, protection policy, minimum PIN length, and resident/discoverable key
     and user verification attributes of cred have been attested by the holder of the private
     counterpart of the public key contained in the credential's x509 certificate.

     Please note that the x509 certificate itself is not verified.

     The attestation statement formats supported by fido_cred_verify() are packed, fido-u2f, and
     tpm.  The attestation type implemented by fido_cred_verify() is Basic Attestation.

     The fido_cred_verify_self() function verifies whether the client data hash, relying party
     ID, credential ID, type, protection policy, minimum PIN length, and resident/discoverable
     key and user verification attributes of cred have been attested by the holder of the
     credential's private key.

     The attestation statement formats supported by fido_cred_verify_self() are packed and
     fido-u2f.  The attestation type implemented by fido_cred_verify_self() is Self Attestation.

     Other attestation formats and types are not supported.

RETURN VALUES

     The error codes returned by fido_cred_verify() and fido_cred_verify_self() are defined in
     <fido/err.h>.  If cred passes verification, then FIDO_OK is returned.

SEE ALSO

     fido_cred_new(3), fido_cred_set_authdata(3)