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_aaguid_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`, `fido_cbor_info_options_value_ptr`, `fido_cbor_info_algorithm_type`, `fido_cbor_info_algorithm_cose`, `fido_cbor_info_algorithm_count`, `fido_cbor_info_aaguid_len`, `fido_cbor_info_extensions_len`, `fido_cbor_info_protocols_len`, `fido_cbor_info_transports_len`, `fido_cbor_info_versions_len`, `fido_cbor_info_options_len`, `fido_cbor_info_maxmsgsiz`, `fido_cbor_info_maxcredbloblen`, `fido_cbor_info_maxcredcntlst`, `fido_cbor_info_maxcredidlen`, `fido_cbor_info_maxlargeblob`, `fido_cbor_info_fwversion` — FIDO2 CBOR Info API

# SYNOPSIS

library “libfido2” libcbor libcrypto libz
`#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);

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

char **
`fido_cbor_info_extensions_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_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);

size_t
`fido_cbor_info_aaguid_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_protocols_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);

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_fwversion`(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_aaguid_ptr`(), `fido_cbor_info_extensions_ptr`(), `fido_cbor_info_protocols_ptr`(), `fido_cbor_info_transports_ptr`(), and `fido_cbor_info_versions_ptr`() functions return pointers to the authenticator attestation GUID, supported extensions, PIN protocol, 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_extensions_len`(), `fido_cbor_info_protocols_len`(), `fido_cbor_info_transports_len`(), or `fido_cbor_info_versions_len`().

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

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

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

# RETURN VALUES

The `fido_cbor_info_aaguid_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_open(3)

July 9, 2025 | Debian