FIDO_CBOR_INFO_NEW(3) | Library Functions Manual | FIDO_CBOR_INFO_NEW(3)

# NAME

`fido_cbor_info_new`, `fido_cbor_info_free`, `fido_dev_get_cbor_info`, `fido_cbor_info_decrypt`, `fido_cbor_info_aaguid_ptr`, `fido_cbor_info_attfmts_ptr`, `fido_cbor_info_encid_ptr`, `fido_cbor_info_id_ptr`, `fido_cbor_info_encstate_ptr`, `fido_cbor_info_state_ptr`, `fido_cbor_info_extensions_ptr`, `fido_cbor_info_pin_policy_url_ptr`, `fido_cbor_info_protocols_ptr`, `fido_cbor_info_reset_transports_ptr`, `fido_cbor_info_transports_ptr`, `fido_cbor_info_versions_ptr`, `fido_cbor_info_options_name_ptr`, `fido_cbor_info_options_value_ptr`, `fido_cbor_info_algorithm_type`, `fido_cbor_info_algorithm_cose`, `fido_cbor_info_algorithm_count`, `fido_cbor_info_certs_name_ptr`, `fido_cbor_info_certs_value_ptr`, `fido_cbor_info_certs_len`, `fido_cbor_info_cfgcmds_ptr`, `fido_cbor_info_cfgcmds_len`, `fido_cbor_info_aaguid_len`, `fido_cbor_info_attfmts_len`, `fido_cbor_info_encid_len`, `fido_cbor_info_id_len`, `fido_cbor_info_encstate_len`, `fido_cbor_info_state_len`, `fido_cbor_info_extensions_len`, `fido_cbor_info_pin_policy_url_len`, `fido_cbor_info_protocols_len`, `fido_cbor_info_reset_transports_len`, `fido_cbor_info_transports_len`, `fido_cbor_info_versions_len`, `fido_cbor_info_options_len`, `fido_cbor_info_long_touch_reset`, `fido_cbor_info_maxmsgsiz`, `fido_cbor_info_maxcredbloblen`, `fido_cbor_info_maxcredcntlst`, `fido_cbor_info_maxcredidlen`, `fido_cbor_info_maxlargeblob`, `fido_cbor_info_maxrpid_minpinlen`, `fido_cbor_info_maxpinlen`, `fido_cbor_info_minpinlen`, `fido_cbor_info_pin_policy`, `fido_cbor_info_fwversion`, `fido_cbor_info_uv_attempts`, `fido_cbor_info_uv_modality`, `fido_cbor_info_uv_count_since_pin`, `fido_cbor_info_rk_remaining`, `fido_cbor_info_new_pin_required` — FIDO2 CBOR Info API

# SYNOPSIS

`#include <fido.h>`

fido_cbor_info_t *
`fido_cbor_info_new`(void);

void
`fido_cbor_info_free`(fido_cbor_info_t **ci_p);

int
`fido_dev_get_cbor_info`(fido_dev_t *dev, fido_cbor_info_t *ci);

int
`fido_cbor_info_decrypt`(fido_cbor_info_t *ci, const unsigned char *ppuat, size_t ppuat_len);

const unsigned char *
`fido_cbor_info_aaguid_ptr`(const fido_cbor_info_t *ci);

char **
`fido_cbor_info_attfmts_ptr`(const fido_cbor_info_t *ci);

const uint8_t *
`fido_cbor_info_cfgcmds_ptr`(const fido_cbor_info_t *ci);

const unsigned char *
`fido_cbor_info_encid_ptr`(const fido_cbor_info_t *ci);

const unsigned char *
`fido_cbor_info_id_ptr`(const fido_cbor_info_t *ci);

const unsigned char *
`fido_cbor_info_encstate_ptr`(const fido_cbor_info_t *ci);

const unsigned char *
`fido_cbor_info_state_ptr`(const fido_cbor_info_t *ci);

char **
`fido_cbor_info_extensions_ptr`(const fido_cbor_info_t *ci);

const unsigned char *
`fido_cbor_info_pin_policy_url_ptr`(const fido_cbor_info_t *ci);

const uint8_t *
`fido_cbor_info_protocols_ptr`(const fido_cbor_info_t *ci);

char **
`fido_cbor_info_reset_transports_ptr`(const fido_cbor_info_t *ci);

char **
`fido_cbor_info_transports_ptr`(const fido_cbor_info_t *ci);

char **
`fido_cbor_info_versions_ptr`(const fido_cbor_info_t *ci);

char **
`fido_cbor_info_options_name_ptr`(const fido_cbor_info_t *ci);

const bool *
`fido_cbor_info_options_value_ptr`(const fido_cbor_info_t *ci);

const char *
`fido_cbor_info_algorithm_type`(const fido_cbor_info_t *ci, size_t idx);

int
`fido_cbor_info_algorithm_cose`(const fido_cbor_info_t *ci, size_t idx);

size_t
`fido_cbor_info_algorithm_count`(const fido_cbor_info_t *ci);

char **
`fido_cbor_info_certs_name_ptr`(const fido_cbor_info_t *ci);

const uint64_t *
`fido_cbor_info_certs_value_ptr`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_certs_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_aaguid_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_attfmts_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_cfgcmds_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_encid_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_id_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_encstate_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_state_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_extensions_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_pin_policy_url_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_protocols_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_reset_transports_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_transports_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_versions_len`(const fido_cbor_info_t *ci);

size_t
`fido_cbor_info_options_len`(const fido_cbor_info_t *ci);

bool
`fido_cbor_info_long_touch_reset`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_maxmsgsiz`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_maxcredbloblen`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_maxcredcntlst`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_maxcredidlen`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_maxlargeblob`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_maxrpid_minpinlen`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_maxpinlen`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_minpinlen`(const fido_cbor_info_t *ci);

int
`fido_cbor_info_pin_policy`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_fwversion`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_uv_attempts`(const fido_cbor_info_t *ci);

uint64_t
`fido_cbor_info_uv_modality`(const fido_cbor_info_t *ci);

int64_t
`fido_cbor_info_uv_count_since_pin`(const fido_cbor_info_t *ci);

int64_t
`fido_cbor_info_rk_remaining`(const fido_cbor_info_t *ci);

bool
`fido_cbor_info_new_pin_required`(const fido_cbor_info_t *ci);

# DESCRIPTION

The `fido_cbor_info_new`() function returns a pointer to a newly allocated, empty fido_cbor_info_t type. If memory cannot be allocated, NULL is returned.

The `fido_cbor_info_free`() function releases the memory backing *ci_p, where *ci_p must have been previously allocated by `fido_cbor_info_new`(). On return, *ci_p is set to NULL. Either ci_p or *ci_p may be NULL, in which case `fido_cbor_info_free`() is a NOP.

The `fido_dev_get_cbor_info`() function transmits a `CTAP_CBOR_GETINFO` command to dev and fills ci with attributes retrieved from the command's response. The `fido_dev_get_cbor_info`() function may block.

The `fido_cbor_info_decrypt`() function decrypts the encrypted fields of ci using the persistent PIN/UV Auth token referenced by ppuat, which must point to at least ppuat_len bytes.

The `fido_cbor_info_aaguid_ptr`(), `fido_cbor_info_attfmts_ptr`(), `fido_cbor_info_cfgcmds_ptr`(), `fido_cbor_info_encid_ptr`(), `fido_cbor_info_id_ptr`(), `fido_cbor_info_encstate_ptr`(), `fido_cbor_info_state_ptr`(), `fido_cbor_info_extensions_ptr`(), `fido_cbor_info_pin_policy_url_ptr`(), `fido_cbor_info_protocols_ptr`(), `fido_cbor_info_reset_transports_ptr`(), `fido_cbor_info_transports_ptr`(), and `fido_cbor_info_versions_ptr`() functions return pointers to the authenticator attestation GUID, supported attestation formats, supported authenticator config commands, encrypted identifier, decrypted identifier, encrypted credential store state, decrypted credential store state, supported extensions, PIN complexity policy URL, PIN protocol, transports for authenticator reset, transports, and CTAP version strings of ci. The corresponding length of a given attribute can be obtained by `fido_cbor_info_aaguid_len`(), `fido_cbor_info_attfmts_len`(), `fido_cbor_info_cfgcmds_len`(), `fido_cbor_info_encid_len`(), `fido_cbor_info_id_len`(), `fido_cbor_info_encstate_len`(), `fido_cbor_info_state_len`(), `fido_cbor_info_extensions_len`(), `fido_cbor_info_pin_policy_url_len`(), `fido_cbor_info_protocols_len`(), `fido_cbor_info_reset_transports_len`(), `fido_cbor_info_transports_len`(), or `fido_cbor_info_versions_len`(). The supported attestation formats, encrypted identifier, PIN complexity policy URL, and transports for authenticator reset attributes are CTAP 2.2 additions. The supported authenticator config commands and encrypted credential store state attributes are CTAP 2.3 additions.

The `fido_cbor_info_options_name_ptr`() and `fido_cbor_info_options_value_ptr`() functions return pointers to the array of option names and their respective values in ci. The length of the options array is returned by `fido_cbor_info_options_len`().

The `fido_cbor_info_algorithm_count`() function returns the number of supported algorithms in ci. The `fido_cbor_info_algorithm_cose`() function returns the COSE identifier of algorithm idx in ci, or 0 if the COSE identifier is unknown or unset. The `fido_cbor_info_algorithm_type`() function returns the type of algorithm idx in ci, or NULL if the type is unset. Please note that the first algorithm in ci has an idx (index) value of 0.

The `fido_cbor_info_certs_name_ptr`() and `fido_cbor_info_certs_value_ptr`() functions return pointers to the array of certification names and their respective values in ci. The length of the certifications array is returned by `fido_cbor_info_certs_len`().

The `fido_cbor_info_maxmsgsiz`() function returns the maximum message size attribute of ci.

The `fido_cbor_info_maxcredbloblen`() function returns the maximum “credBlob” length in bytes supported by the authenticator as reported in ci.

The `fido_cbor_info_maxcredcntlst`() function returns the maximum supported number of credentials in a single credential ID list as reported in ci.

The `fido_cbor_info_maxcredidlen`() function returns the maximum supported length of a credential ID as reported in ci.

The `fido_cbor_info_maxrpid_minpinlen`() function returns the maximum number of RP IDs that may be passed to fido_dev_set_pin_minlen_rpid(3), as reported in ci. The minimum PIN length attribute is a CTAP 2.1 addition. If the attribute is not advertised by the authenticator, the `fido_cbor_info_maxrpid_minpinlen`() function returns zero.

The `fido_cbor_info_maxlargeblob`() function returns the maximum length in bytes of an authenticator's serialized largeBlob array as reported in ci.

The `fido_cbor_info_maxpinlen`() function returns the maximum PIN length enforced by the authenticator as reported in ci. The maximum PIN length attribute is a CTAP 2.2 addition. If the attribute is not advertised by the authenticator, the `fido_cbor_info_maxpinlen`() function returns zero.

The `fido_cbor_info_minpinlen`() function returns the minimum PIN length enforced by the authenticator as reported in ci. The minimum PIN length attribute is a CTAP 2.1 addition. If the attribute is not advertised by the authenticator, the `fido_cbor_info_minpinlen`() function returns zero.

The `fido_cbor_info_pin_policy`() function returns information about whether an additional PIN complexity policy is enforced by the authenticator, as reported by ci. The PIN complexity policy attribute is a CTAP 2.2 addition. The value is 1 if an additional policy is enforced, 0 if no such policy is enforced, or -1 if the feature is not supported by the authenticator.

The `fido_cbor_info_fwversion`() function returns the firmware version attribute of ci.

The `fido_cbor_info_uv_attempts`() function returns the number of UV attempts that the platform may attempt before falling back to PIN authentication. If 1, then all fido_dev_get_uv_retry_count(3) retries are handled internally by the authenticator and the platform may only attempt non-PIN UV once. The UV attempts attribute is a CTAP 2.1 addition. If the attribute is not advertised by the authenticator, the `fido_cbor_info_uv_attempts`() function returns zero.

The `fido_cbor_info_uv_count_since_pin`() function returns the number of built-in UV operations since the last PIN entry. The UV count since last PIN entry attribute is a CTAP 2.2 addition. If the attribute is not advertised by the authenticator, the `fido_cbor_info_uv_count_since_pin`() function returns -1.

The `fido_cbor_info_uv_modality`() function returns a bitmask representing different UV modes supported by the authenticator, as defined in the FIDO Registry of Predefined Values and reported in ci. See the FIDO_UV_MODE_* definitions in `<fido/param.h>` for the set of values defined by libfido2 and a brief description of each. The UV modality attribute is a CTAP 2.1 addition. If the attribute is not advertised by the authenticator, the `fido_cbor_info_uv_modality`() function returns zero.

The `fido_cbor_info_rk_remaining`() function returns the estimated number of additional resident/discoverable credentials that can be stored on the authenticator as reported in ci. The estimated number of remaining resident credentials is a CTAP 2.1 addition. If the attribute is not advertised by the authenticator, the `fido_cbor_info_rk_remaining`() function returns -1.

The `fido_cbor_info_new_pin_required`() function returns whether a new PIN is required by the authenticator as reported in ci. If `fido_cbor_info_new_pin_required`() returns true, operations requiring PIN authentication will fail until a new PIN is set on the authenticator. The fido_dev_set_pin(3) function can be used to set a new PIN.

The `fido_cbor_info_long_touch_reset`() function returns true if a long touch is required to reset the authenticator. The long touch for reset attribute is a CTAP 2.2 addition. If the attribute is not advertised by the authenticator, the `fido_cbor_info_long_touch_reset`() function returns false.

A complete example of how to use these functions can be found in the example/info.c file shipped with libfido2.

# RETURN VALUES

The error codes returned by `fido_dev_get_cbor_info`() and `fido_cbor_info_decrypt`() are defined in `<fido/err.h>`. On success, `FIDO_OK` is returned.

The `fido_cbor_info_aaguid_ptr`(), `fido_cbor_info_encid_ptr`(), `fido_cbor_info_encstate_ptr`(), `fido_cbor_info_extensions_ptr`(), `fido_cbor_info_protocols_ptr`(), `fido_cbor_info_transports_ptr`(), `fido_cbor_info_versions_ptr`(), `fido_cbor_info_options_name_ptr`(), and `fido_cbor_info_options_value_ptr`() functions return NULL if the respective field in ci is absent. If not NULL, returned pointers are guaranteed to exist until any API function that takes ci without the const qualifier is invoked.

# SEE ALSO

fido_dev_get_puat(3), fido_dev_get_uv_retry_count(3), fido_dev_open(3), fido_dev_set_pin(3), fido_dev_set_pin_minlen_rpid(3)

FIDO Registry of Predefined Values, https://fidoalliance.org/specs/common-specs/fido-registry-v2.2-rd-20210525.html, FIDO Alliance, 2021-05-25, Review Draft, Version 2.2.

March 26, 2026 | Yubico AB