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83 lines
3.3 KiB
Markdown
83 lines
3.3 KiB
Markdown
# Tillitis Key
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## Introduction
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Tillitis Key (TKey) is a new kind of USB security token. What makes
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the TKey unique is that it allows a user to load and run applications on
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the device, while still providing security. This allow for open-ended,
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flexible usage. Given the right application, the TKey can support use
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cases such as SSH login, Ed25519 signing, Root of Trust, FIDO2, TOTP,
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Passkey, and more.
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During the load operation, the device measures the application
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(calculates a cryptographic hash digest over it) before running
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it on the open hardware security processor. This measurement
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is similar to [TCG DICE](https://trustedcomputinggroup.org/work-groups/dice-architectures/).
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Each Tkey device contains a Unique Device Secret (UDS), which
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together with the application measurement, and an optional
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user-provided seed, is used to derive key material unique to each
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application. This guarantees that if the integrity of the application
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loaded onto the device has been tampered with, the correct keys
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needed for an authentication will not be generated.
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Key derivation with a user-provided seed allows users to build and
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load their own apps, while ensuring that each app loaded will have
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its own cryptographic identity, and can also be used for authentication
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towards different services.
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The Tkey platform is based around a 32-bit RISC-V processor and has
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128 KB of RAM. The current firmware is designed to load an app that is
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up to 100 KB in size, and gives it a stack of 28 KB. A smaller app may
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move itself in memory to get larger continuous memory.
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All of the Tkey software, firmware, FPGA Verilog source code, schematics
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and PCB design files are open source. Like all trustworthy security software
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and hardware should be. This in itself makes it different, as other
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security tokens utilize at least some closed source hardware for its
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security-critical operations.
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*The TK1 PCB, the first implementation of the TKey.*
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## Documentation
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### Getting started
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* [Quickstart](doc/quickstart.md) to program the TKey
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* [Toolchain setup](doc/toolchain_setup.md)
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* [Release Notes](doc/release_notes.md)
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### In-depth technical information
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* [System Description](doc/system_description/system_description.md)
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* [Threat Model](doc/threat_model/threat_model.md)
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* [Framing Protocol](doc/framing_protocol/framing_protocol.md)
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* [Boards](doc/system_description/boards.md)
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* [Firmware](doc/system_description/firmware.md)
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* [Software](doc/system_description/software.md)
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Note that development is ongoing. For example, changes might be made
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to the measuring and derivation of key material, causing the
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public/private keys of a signer app to change. To avoid unexpected
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changes, please use a tagged release. Read the [Release
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Notes](doc/release_notes.md) to keep up to date with changes and new
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releases.
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Applications and host programs that communicate with the apps are kept
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in this repository: https://github.com/tillitis/tillitis-key1-apps
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## About this repository
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This repository contains hardware, software and utilities written as
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part of the TKey. It is structured as monolithic repository, or
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"monorepo", where all components live in one repository.
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## Licensing
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See [LICENSES](./LICENSES/README.md) for more information about
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the projects' licenses.
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All contributors must adhere to the [Developer Certificate of Origin](dco.md).
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