u2f.h

Go to the documentation of this file.

// U2F/CTAP1 Protocol Implementation
// Legacy U2F support for Chrome compatibility
 
#pragma once
#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
// ============================================================================
// U2F Constants
// ============================================================================
 
// U2F Command bytes (INS)
#define U2F_INS_REGISTER        0x01
#define U2F_INS_AUTHENTICATE    0x02
#define U2F_INS_VERSION         0x03
 
// U2F Authentication control bytes (P1)
#define U2F_AUTH_CHECK_ONLY     0x07    // Check if key handle valid
#define U2F_AUTH_ENFORCE        0x03    // Sign with user presence
#define U2F_AUTH_DONT_ENFORCE   0x08    // Sign without user presence (not recommended)
 
// U2F Status Words (SW1 || SW2)
#define U2F_SW_NO_ERROR                 0x9000
#define U2F_SW_CONDITIONS_NOT_SATISFIED 0x6985  // User presence required
#define U2F_SW_WRONG_DATA               0x6A80  // Invalid key handle
#define U2F_SW_WRONG_LENGTH             0x6700
#define U2F_SW_CLA_NOT_SUPPORTED        0x6E00
#define U2F_SW_INS_NOT_SUPPORTED        0x6D00
#define U2F_SW_WRONG_P1P2              0x6B00
#define U2F_SW_WTF                     0x6F00  // Internal error
 
// U2F Sizes
#define U2F_CHALLENGE_SIZE      32
#define U2F_APPLICATION_SIZE    32
#define U2F_KEY_HANDLE_SIZE     64      // Match FIDO2 credential ID
#define U2F_REGISTER_ID         0x05    // Registration reserved byte
#define U2F_EC_POINT_SIZE       65      // 0x04 || X || Y (uncompressed)
#define U2F_EC_KEY_SIZE         32      // P-256 key component
#define U2F_MAX_ATT_CERT_SIZE   1024
#define U2F_MAX_EC_SIG_SIZE     72      // DER encoded ECDSA signature
#define U2F_CTR_SIZE            4       // Counter size
 
// ============================================================================
// Functions
// ============================================================================

bool u2f_init_attestation(void);

bool u2f_get_attestation_cert(const uint8_t **cert, uint16_t *cert_len);

bool u2f_attestation_sign(const uint8_t *data, size_t data_len,
                          uint8_t *signature, uint8_t *sig_len);

uint16_t u2f_process_apdu(const uint8_t *apdu, uint16_t apdu_len,
                          uint8_t *response, uint16_t response_max);
 
#ifdef __cplusplus
}
#endif