Sign.ino

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

#include <CryptnoxWallet.h>
#include <SPI.h>

#define PN532_SS_PIN  (10U)

#define DEMO_PIN      "000000000"

ArduinoLoggerAdapter   serialAdapter;

PN532Adapter           nfc(serialAdapter, PN532_SS_PIN, &SPI);

ArduinoCryptoProvider  cryptoProvider;

ArduinoPlatform        platform;

CryptnoxWallet         wallet(nfc, serialAdapter, cryptoProvider, platform);

void setup() {
    serialAdapter.begin(115200);
    delay(1000);                              /* Arduino R4: wait for Serial */
    SPI.begin();
 
    if (!wallet.begin()) {
        serialAdapter.println(F("PN532 init failed"));
        while (1);
    }
}

void loop() {
    CW_SecureSession session;
    if (!wallet.connect(session)) {
        serialAdapter.println(F("Card not detected"));
        wallet.disconnect(session);
        delay(1000);
        return;
    }
 
    uint8_t hash[CW_HASH_SIZE];
    memset(hash, 0x01, sizeof(hash));   /* replace with SHA-256 of your tx */
 
    CW_SignRequest req(session,
                       CW_SIGN_CURR_K1,
                       CW_SIGN_SIG_ECDSA_LOW_S,
                       CW_SIGN_WITH_PIN);
    req.hash       = hash;
    req.hashLength = sizeof(hash);
    CW_Utils::safe_memcpy(req.pin, sizeof(req.pin),
                          reinterpret_cast<const uint8_t*>(DEMO_PIN), strlen(DEMO_PIN));
 
    CW_SignResult sig = wallet.sign(req);
    if (sig.errorCode == CW_OK) {
        serialAdapter.println(F("Signature OK"));
 
        serialAdapter.print(F("  r = "));
        for (uint8_t i = 0U; i < 32U; i++) {
            uint8_t b = sig.signature[CW_SIG_R_OFFSET + i];
            if (b < 0x10U) { serialAdapter.print(F("0")); }
            serialAdapter.print(b, HEX);
        }
        serialAdapter.println();
 
        serialAdapter.print(F("  s = "));
        for (uint8_t i = 0U; i < 32U; i++) {
            uint8_t b = sig.signature[CW_SIG_S_OFFSET + i];
            if (b < 0x10U) { serialAdapter.print(F("0")); }
            serialAdapter.print(b, HEX);
        }
        serialAdapter.println();
 
        serialAdapter.print(F("  errorCode = 0x"));
        serialAdapter.println(sig.errorCode, HEX);
    } else if (sig.errorCode == CW_SIGN_PIN_INCORRECT) {
        /* CRITICAL: do NOT loop — each wrong PIN attempt burns a retry. */
        serialAdapter.println(F("Wrong PIN — halting to protect retry counter"));
        CW_Utils::secure_wipe(hash, sizeof(hash));
        CW_Utils::secure_wipe(sig.signature, sizeof(sig.signature));
        wallet.disconnect(session);
        while (1);
    } else {
        serialAdapter.print(F("Sign failed: 0x"));
        serialAdapter.println(sig.errorCode, HEX);
    }
 
    CW_Utils::secure_wipe(hash, sizeof(hash));
    CW_Utils::secure_wipe(sig.signature, sizeof(sig.signature));
    wallet.disconnect(session);
    delay(1000);
}