cryptnox-sdk-cpp

cryptnox-sdk-cpp

Platform-independent C++ core SDK for Cryptnox Hardware Wallet

cryptnox-sdk-cpp is the shared C++ core SDK for the Cryptnox Hardware Wallet. It implements the card-side protocol — secure channel establishment (SELECT → certificate → ECDH → mutual auth), APDU framing, PIN verification, signing, and user-data writing — independently of any target platform, NFC reader, or crypto library.

Important

This SDK is not usable on its own. It exposes three abstract interfaces (CW_NfcTransport, CW_CryptoProvider, CW_Logger) that must be implemented by a host integration. It ships no transport driver, no crypto backend, and no logging output.

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Used by

This core is consumed as a submodule by the platform-specific SDKs:

Integration	Repository
ESP32-S3 (ESP-IDF v5.5)	cryptnox/cryptnox-sdk-esp32
Arduino R4 (Renesas RA4M1)	cryptnox/cryptnox-sdk-arduino

If you want to talk to a Cryptnox card on real hardware, start from one of those repositories.

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Porting to a new platform

This repository is intended as the starting point for porting the SDK to a new platform (another MCU family, a desktop OS, a different NFC reader, a different crypto backend, etc.).

A port consists of providing concrete implementations of the three adapter interfaces:

Interface	What you must provide
CW_NfcTransport	Driver for your NFC reader (PN532, PN7150, PC/SC, …)
CW_CryptoProvider	SHA-256/512, AES-CBC, ECDH, EC key generation, RNG (mbedTLS, BearSSL, OpenSSL, hardware peripheral, …)
CW_Logger	Output sink (UART, stdout, syslog, network, …)

Then drop this repository in as a submodule (or copy of its sources) inside your project, build it together with your adapters, and instantiate CryptnoxWallet with the three injected dependencies. The existing platform SDKs (cryptnox-sdk-esp32, cryptnox-sdk-arduino) are useful references for a complete port.

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What's inside

File	Role
CryptnoxWallet.{h,cpp}	High-level API: begin, connect, verifyPin, sign, writeUserData, disconnect
CW_SecureChannel.{h,cpp}	Secure channel protocol (mutual auth, session keys, encrypted APDU exchange)
CW_NfcTransport.h	Adapter interface — NFC reader contract
CW_CryptoProvider.h	Adapter interface — SHA-256/512, AES-CBC, ECDH, EC keygen, RNG
CW_Logger.h	Adapter interface — debug/serial output
CW_TrustedKeys.h	Cryptnox CA public keys used to verify card certificates
CW_Defs.h, CW_Utils.{h,cpp}	Constants, error codes, small helpers
platform_compat.h	Shim for non-Arduino targets

The three adapter interfaces are the only contract a host must satisfy. Everything else is self-contained.

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Integrating the core

A host integration injects its three adapters into CryptnoxWallet:

#include "CryptnoxWallet.h"
 
// MyXxx = concrete adapters provided by the platform SDK:
//   - MyNfcTransport   : public CW_NfcTransport
//   - MyCryptoProvider : public CW_CryptoProvider
//   - MyLogger         : public CW_Logger
 
MyLogger          logger;
MyCryptoProvider  crypto;
MyNfcTransport    transport(/* platform-specific args */);
CryptnoxWallet    wallet(transport, logger, crypto);
 
if (!wallet.begin()) { /* reader init failed */ }
 
CW_SecureSession session;
if (wallet.connect(session)) {
    // wallet.verifyPin(...), wallet.sign(...), wallet.writeUserData(...)
    wallet.disconnect(session);
}

Full runnable examples (PIN verify, transaction signing, full ESP-IDF / Arduino boilerplate) live in the platform SDKs linked above.

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Building standalone

There is no standalone build target in this repository. The CI workflow runs cppcheck static analysis only (.github/workflows/static_analysis.yml); host-supplied headers (uECC.h, mbedtls/*, platform logger) are not vendored, so missingInclude is suppressed.

To compile and exercise the code, use one of the platform SDKs.

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Documentation

The generated documentation for this project is available here.

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License

cryptnox-sdk-cpp is dual-licensed:

• LGPL-3.0 for open-source projects and proprietary projects that comply with LGPL requirements
• Commercial license for projects that require a proprietary license without LGPL obligations

For commercial inquiries, contact: conta.nosp@m.ct@c.nosp@m.ryptn.nosp@m.ox.c.nosp@m.om