// Credential IDs are self-contained: the private key is re-derived from the
// device master secret, so non-resident credentials need no storage.
//
//   credential ID = version (1) || nonce (32) || tag (16)
//   private key   = HMAC(master, "skey-key" || version || nonce || rpIdHash)
//   tag           = HMAC(master, "skey-tag" || version || nonce || rpIdHash)
#pragma once

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#define CRED_ID_LEN 49

// Makes a new credential bound to rp_id_hash.
bool cred_create(const uint8_t rp_id_hash[32], uint8_t cred_id[CRED_ID_LEN], uint8_t priv[32], uint8_t pub[64]);

// Recovers the private key if this device issued cred_id for rp_id_hash.
bool cred_unwrap(const uint8_t rp_id_hash[32], const uint8_t *cred_id, size_t len, uint8_t priv[32]);