fido2.h

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// FIDO2/WebAuthn Module
// Main interface for credential management and user presence
 
#pragma once
#include <stdint.h>
#include <stdbool.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
// ============================================================================
// Constants
// ============================================================================
 
#define FIDO2_MAX_CREDENTIALS   32      // Max ECC slots (runtime range provided by module registry)
#define FIDO2_RP_ID_MAX_LEN     64
#define FIDO2_USER_ID_MAX_LEN   64
#define FIDO2_USER_NAME_MAX_LEN 32
#define FIDO2_CRED_ID_LEN       64      // Credential ID length
 
// Curve identifiers
#define CDC_CURVE_ED25519 0
#define CDC_CURVE_P256    1
 
// ============================================================================
// Types
// ============================================================================
 
typedef enum {
    FIDO2_UP_PENDING = 0,   // Waiting for user
    FIDO2_UP_APPROVED,      // User approved
    FIDO2_UP_DENIED,        // User denied
    FIDO2_UP_TIMEOUT        // Timeout waiting for user
} fido2_user_presence_result_t;
 
typedef enum {
    FIDO2_ACTION_REGISTER = 0,  // makeCredential, new credential
    FIDO2_ACTION_AUTHENTICATE,  // getAssertion
    FIDO2_ACTION_SELECT,        // Device selection (authenticatorSelection 0x0B / make.me.blink probe) - user presence only, no PIN
    FIDO2_ACTION_OVERWRITE      // makeCredential replacing an existing resident credential
} fido2_action_t;
 
#ifdef __DOXYGEN__
namespace cdc::mod_fido2 {
#endif
 
// Credential info (for listing - no private key data)
typedef struct {
    uint8_t slot;                           // Logical slot index (0..count-1)
    char rp_id[FIDO2_RP_ID_MAX_LEN];        // Relying Party ID (e.g., "github.com" or "ssh:server")
    uint8_t rp_id_hash[32];                 // SHA-256 of RP ID
    char user_name[FIDO2_USER_NAME_MAX_LEN]; // Display name
    uint8_t user_id[FIDO2_USER_ID_MAX_LEN]; // User handle
    uint8_t user_id_len;
    uint32_t sign_count;                    // Per-credential counter
    bool resident_key;                      // Is discoverable credential
    uint8_t cred_protect;                   // Credential protection level
    uint8_t curve;                          // CDC_CURVE_P256 or CDC_CURVE_ED25519
} fido2_credential_info_t;
 
#ifdef __DOXYGEN__
} // namespace cdc::mod_fido2
#endif
 
// User presence callback type
typedef fido2_user_presence_result_t (*fido2_user_presence_cb_t)(
    const char *rp_id,
    fido2_action_t action,
    const char *user_name
);
 
// ============================================================================
// Initialization
// ============================================================================

bool fido2_init(void);

void fido2_set_user_presence_callback(fido2_user_presence_cb_t cb);

fido2_user_presence_result_t fido2_request_user_presence(
    const char *rp_id,
    fido2_action_t action,
    const char *user_name
);

void fido2_set_pin_verified(bool verified);
bool fido2_is_pin_verified(void);
 
// ============================================================================
// Credential Management
// ============================================================================

uint8_t fido2_get_credential_count(void);

bool fido2_get_credential_info(uint8_t index, fido2_credential_info_t *info);

uint8_t fido2_find_credentials_by_rp(const uint8_t *rp_id_hash,
                                      uint8_t *out_indices, uint8_t max_indices);

bool fido2_delete_credential(uint8_t slot);

bool fido2_factory_reset(void);
 
// ============================================================================
// Authentication Counter
// ============================================================================

uint32_t fido2_get_auth_counter(void);

void fido2_increment_auth_counter(void);
 
// ============================================================================
// Status
// ============================================================================

bool fido2_is_initialized(void);

uint8_t fido2_get_available_slots(void);
 
#ifdef __cplusplus
}
#endif