FIDO_CRED_EXCLUDE(3)

💖 FIDO_CRED_EXCLUDE 💖

okay bestie, sit down, hydrate, and let me tell you about fido_cred_exclude and fido_cred_empty_exclude_list — the two functions that manage exclude lists in a FIDO2 credential. yes, that's the whole vibe. it's giving gatekeeping but make it cryptography ✨

🌸 SYNOPSIS 🌸

#include <fido.h>

int
fido_cred_exclude(fido_cred_t *cred, const unsigned char *ptr,
    size_t len);

int
fido_cred_empty_exclude_list(fido_cred_t *cred);

🦋 DESCRIPTION 🦋

✨ fido_cred_exclude() ✨

so fido_cred_exclude() takes ptr and adds it to the list of credentials that cred is excluding, where ptr points to a credential ID that's len bytes long. it makes a copy of ptr, okay? like it does NOT keep any references to the pointer you passed in. she's independent, she's self-sufficient, she doesn't need you 💅

and if fido_cred_exclude() fails? no worries bestie, the existing list of excluded credentials is preserved. nothing gets messed up, we don't do chaos here 🫶

now here's the iconic part: if fido_cred_exclude returns success and cred gets passed to fido_dev_make_cred(3) later, on a device that already contains the credential denoted by ptr... then fido_dev_make_cred(3) will fail. periodt. that's the whole point. it's a vibe check and the device did not pass 😭

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

🎀 fido_cred_empty_exclude_list() 🎀

and fido_cred_empty_exclude_list()? she empties the list of credentials excluded by cred. clean slate. reset era. main character energy 🌈

⭐ RETURN VALUES ⭐

the error codes returned by fido_cred_exclude() and fido_cred_empty_exclude_list() are defined in <fido/err.h>. and on success? you get FIDO_OK back, which is honestly the only response we accept in this house 👑

ngl bestie, check your return values. always. no cap. 💀

👀 SEE ALSO 👀

• fido_cred_new(3)
• fido_cred_set_authdata(3)
• fido_dev_make_cred(3)

that's the whole page, bestie — go forth and exclude credentials responsibly ✨💖🎀🦋🌸

this page came from Debian, dated December 2, 2022, and it lives in the FIDO_CRED_EXCLUDE(3) corner of the manual. mwah, slay, bye 🫶💅