CW_SecureChannel.h

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/*
 * SPDX-License-Identifier: LGPL-3.0-or-later
 * Copyright (c) 2026 Cryptnox SA
 */

 
#ifndef CW_SECURECHANNEL_H
#define CW_SECURECHANNEL_H
 
/******************************************************************
 * 1. Public constants
 ******************************************************************/
 
#define CW_PAIRING_DATA       "Cryptnox Basic CommonPairingData"
#define CW_PAIRING_DATA_BYTES (sizeof(CW_PAIRING_DATA) - 1U)
 
/******************************************************************
 * 2. Included files
 ******************************************************************/
 
#include "platform_compat.h"
#include "CW_NfcTransport.h"
#include "CW_Logger.h"
#include "CW_CryptoProvider.h"
#include "CW_Platform.h"
#include "CW_Defs.h"          /* for CW_SecureSession, CW_Curve, and constants */
 
/******************************************************************
 * 2. Class declaration
 ******************************************************************/

class CW_SecureChannel {
public:
    CW_SecureChannel(CW_NfcTransport& driver, CW_Logger& logger,
                     CW_CryptoProvider& crypto, CW_Platform& platform);
 
    CW_SecureChannel(const CW_SecureChannel&) = delete;
    CW_SecureChannel& operator=(const CW_SecureChannel&) = delete;

    bool begin();

    bool inListPassiveTarget();

    void resetReader();

    bool printFirmwareVersion();

    bool selectApdu();

    bool getCardCertificate(uint8_t* cardCertificate, uint8_t& cardCertificateLength);

    bool extractCardEphemeralKey(const uint8_t* cardCertificate,
                                 uint8_t* cardEphemeralPubKey,
                                 uint8_t* fullEphemeralPubKey65 = NULL);

    bool openSecureChannel(uint8_t* salt,
                           uint8_t* clientPublicKey,
                           uint8_t* clientPrivateKey,
                           CW_Curve sessionCurve);

    bool mutuallyAuthenticate(CW_SecureSession& session,
                              const uint8_t* salt,
                              uint8_t* clientPublicKey,
                              const uint8_t* clientPrivateKey,
                              CW_Curve sessionCurve,
                              const uint8_t* cardEphemeralPubKey);

    bool getManufacturerCertificate(uint8_t* cert, uint16_t& certLen);

    bool preFetchManufacturerCert();

    uint8_t verifyCertificateChain(const uint8_t* cardCert, uint8_t cardCertLen);

    bool aesCbcEncrypt(CW_SecureSession& session,
                       const uint8_t apdu[], uint16_t apduLength,
                       const uint8_t data[], uint16_t dataLength,
                       uint8_t* decryptedOutput = NULL,
                       uint16_t* decryptedOutputLength = NULL);

    bool aesCbcDecrypt(const CW_SecureSession& session,
                       uint8_t* response, size_t responseLen,
                       uint8_t* macValue,
                       uint8_t* decryptedOutput = NULL,
                       uint16_t* decryptedOutputLength = NULL);

    bool checkStatusWord(const uint8_t* response, uint16_t responseLength,
                         uint8_t sw1Expected, uint8_t sw2Expected);
 
private:
    CW_NfcTransport&   _driver;   
    CW_Logger&         _logger;   
    CW_CryptoProvider& _crypto;   
    CW_Platform&       _platform; 

    uint8_t _lastNonce[CW_CERT_NONCE_SIZE];

    uint16_t _cachedMfCertLen;
 
    static bool parseDerSigToRaw(const uint8_t* der, uint8_t derLen,
                                 uint8_t* raw64);
 
    bool verifyEcdsaSha256(const uint8_t* pubKey64,
                           const uint8_t* message, uint16_t msgLen,
                           const uint8_t* derSig, uint8_t derSigLen);
 
#ifdef CW_FUZZ_BUILD
    friend struct DerFuzzTarget;
#endif
};
 
#endif // CW_SECURECHANNEL_H