avp-tropic

TROPIC01 Hardware Abstraction Layer for AVP
Secure element SDK for Agent Vault Protocol hardware implementations

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Overview

avp-tropic is the TROPIC01 Hardware Abstraction Layer (HAL) for the AVP ecosystem. It provides the low-level SDK for communicating with TROPIC01 secure elements, which power the hardware security backends in AVP implementations like NexusClaw.

This library is based on Tropic Square's libtropic, adapted and extended for AVP protocol integration.

Role in the AVP Ecosystem

+------------------+     +------------------+     +------------------+
|   AI Agent       |     |   AVP Client     |     |   avp-tropic     |
|  (LangChain,     | --> |  (avp-py,        | --> |  (This library)  |
|   CrewAI, etc.)  |     |   avp-rs, etc.)  |     |                  |
+------------------+     +------------------+     +--------+---------+
                                                          |
                                                          | SPI
                                                          v
                                              +------------------+
                                              |   TROPIC01       |
                                              |   Secure Element |
                                              +------------------+

avp-tropic handles:

• SPI communication with TROPIC01 chips
• Secure session establishment (L2 encrypted channel)
• Key storage and retrieval commands
• Cryptographic operations (sign, verify, encrypt)
• Attestation and device authentication

Related Projects

Project	Description
NexusClaw	Production USB hardware security key using avp-tropic
avp-hardware	Reference hardware designs and firmware
AVP Specification	Protocol specification for hardware extensions

Supported Hardware

Development Boards

Board	MCU	Status
Secure Tropic Click	Various (click board)	Supported
STM32U5 Discovery + Tropic Click	STM32U585	Supported
Custom NexusClaw PCB	STM32U535	In Development

Secure Element

Element	Features	Status
TROPIC01	128 slots, ECC P-256/Ed25519, AES-256-GCM, SHA-3, TRNG	Supported

Features

• Hardware Abstraction Layer — Platform-independent HAL for host MCUs
• Crypto Abstraction Layer — Pluggable cryptographic backends
• Secure Sessions — Encrypted L2 communication with TROPIC01
• Multi-Platform — STM32, nRF, ESP32, Linux, and more

Compatibility

For the library to function correctly with TROPIC01, component versions must be compatible:

avp-tropic	Application FW	SPECT FW	Bootloader FW	Status
3.1.0	1.0.0-2.0.0	1.0.0	2.0.1	Current
3.0.0	1.0.0-2.0.0	1.0.0	2.0.1	Supported
2.0.1	1.0.0-1.0.1	1.0.0	2.0.1	Supported

Warning: Using mismatched versions may result in unpredictable behavior. Always use compatible versions.

Repository Structure

avp-tropic/
├── avp/                # AVP protocol layer (added for AVP integration)
├── cal/                # Crypto Abstraction Layer implementations
├── hal/                # Hardware Abstraction Layer implementations
│   └── stm32/          # STM32 HAL
├── include/            # Public API headers
├── src/                # Core library source
├── examples/           # Example projects
│   └── stm32/          # STM32 examples
├── tests/              # Functional tests
├── docs/               # Documentation
└── vendor/             # Third-party dependencies

Getting Started

Prerequisites

# ARM toolchain
apt install gcc-arm-none-eabi

# CMake
apt install cmake

Building

mkdir build && cd build
cmake ..
make

Example: STM32U5 with Tropic Click

cd examples/stm32/stm32u5_tropic_click
make

See the examples README for detailed instructions.

AVP Integration

To use avp-tropic in an AVP hardware implementation:

#include "avp_tropic.h"

// Initialize TROPIC01 interface
lt_handle_t handle;
lt_init(&handle);

// Open secure session
lt_open_session(&handle, pairing_key);

// Store an AVP secret
lt_slot_write(&handle, slot_id, secret_data, secret_len);

// Retrieve an AVP secret
lt_slot_read(&handle, slot_id, buffer, &buffer_len);

// Sign data (key never leaves chip)
lt_ecc_sign(&handle, key_slot, hash, signature);

Documentation

• API Reference — Original libtropic documentation
• AVP Hardware Spec — AVP hardware extension specification
• TROPIC01 Datasheet — Secure element documentation

Contributing

We welcome contributions! Areas where help is needed:

• HAL ports — New microcontroller platforms
• Testing — Integration tests with different hardware
• Documentation — Tutorials and examples

See CONTRIBUTING.md for guidelines.

License

This project is licensed under Apache 2.0. See LICENSE for details.

Original libtropic code is from Tropic Square, used under their open-source license.

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AVP Specification · NexusClaw · AVP Hardware

_{Part of the Agent Vault Protocol ecosystem}