FIDO\_ASSERT\_ALLOW\_CRED(3) Library Functions Manual FIDO\_ASSERT\_ALLOW\_CRED(3)

# [NAME](#NAME)

`fido_assert_allow_cred`, `fido_assert_empty_allow_list` — manage allow lists in a FIDO2 assertion

# [SYNOPSIS](#SYNOPSIS)

`#include <fido.h>`

`int`  
`fido_assert_allow_cred`(`fido_assert_t *assert`, `const unsigned char *ptr`, `size_t len`);

`int`  
`fido_assert_empty_allow_list`(`fido_assert_t *assert`);

# [DESCRIPTION](#DESCRIPTION)

The [`fido_assert_allow_cred`](#fido_assert_allow_cred)() function adds `ptr` to the list of credentials allowed in `assert`, where `ptr` points to a credential ID of `len` bytes. A copy of `ptr` is made, and no references to the passed pointer are kept. If `fido_assert_allow_cred`() fails, the existing list of allowed credentials is preserved.

For the format of a FIDO2 credential ID, please refer to the Web Authentication (webauthn) standard.

The [`fido_assert_empty_allow_list`](#fido_assert_empty_allow_list)() function empties the list of credentials allowed in `assert`.

# [RETURN VALUES](#RETURN_VALUES)

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

# [SEE ALSO](#SEE_ALSO)

[fido\_assert\_new(3)](/man/os/libfido2/fido_assert_new.3), [fido\_assert\_set\_authdata(3)](/man/os/libfido2/fido_assert_set_authdata.3), [fido\_dev\_get\_assert(3)](/man/os/libfido2/fido_dev_get_assert.3)

December 1, 2022 Linux 4.19.0-gvisor

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Document: fido_assert_allow_cred(3) from libfido2 1.17.0-r8 (Chainguard OS)
Source: https://github.com/Yubico/libfido2