feat: offline signer

[SWvheerden]

Description

Adds a stand alone binary to do offline signing

fixes: #7630

[gemini-code-assist]

Summary of Changes

Hello @SWvheerden, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request delivers a critical security enhancement by introducing a dedicated offline transaction signer. The new minotari_offline_signer binary enables users to sign one-sided Tari transactions on a secure, potentially air-gapped machine, significantly reducing the risk of private key exposure. It integrates OS-level secure storage mechanisms and strong cryptographic primitives to protect user keys, offering a robust solution for high-security transaction workflows.

Highlights

• New Offline Signer Binary: Introduces minotari_offline_signer, a standalone tool for securely signing one-sided Tari transactions without an online wallet.
• Secure Key Management: Implements robust key storage using OS-specific keystores (Keychain, Credential Manager, Secret Service) with passphrase-based encryption (Argon2id for key derivation, ChaCha20-Poly1305 for encryption).
• Flexible Initialization: Allows users to initialize the signer with either direct private spend/view keys or by deriving them from BIP39 seed words.
• Comprehensive CLI: Provides a command-line interface with init, sign, status, and clear commands for managing keys and signing transactions.
• Air-Gapped Workflow Support: Designed to facilitate an air-gapped signing process, enhancing security for sensitive transactions.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request introduces a new minotari_offline_signer binary, enabling secure offline signing of Tari transactions. The implementation leverages strong cryptographic primitives like Argon2id and ChaCha20-Poly1305 for key derivation and encryption, along with OS-native secure storage (Keychain, Credential Manager, Secret Service). The CLI provides a user-friendly interface with interactive prompts for sensitive data, and the accompanying README.md offers comprehensive usage instructions and critical security recommendations. Overall, this is a well-designed and important feature for enhancing transaction security.