✨ Set up Copilot instructions for the repository

[Copilot]

Overview

This PR adds comprehensive GitHub Copilot instructions to guide AI-assisted development in this repository, following the best practices documented at https://gh.io/copilot-coding-agent-tips.

What's Added

Created .github/copilot-instructions.md (183 lines) with detailed guidance covering:

📋 Project Context

• Architecture overview: Node.js backend with vanilla JavaScript frontend
• Tech stack: Node.js crypto module, crystals-kyber-js for post-quantum encryption
• File organization: Clear mapping of where different cryptographic functions live

🔐 Security Guidelines (Critical for Cryptography Projects)

Since this repository handles cryptographic operations, the instructions emphasize:

• Never committing secrets or private keys
• Proper input validation before cryptographic operations
• Using secure random number generation (crypto.randomBytes())
• Careful handling of sensitive data
• HTTPS requirements for production deployments
• Input sanitization best practices

💻 Development Guidance

• Code style conventions: JavaScript patterns, API endpoint design, frontend development
• Common tasks: How to add hash functions, modify encryption algorithms, update UI
• Workflow: Getting started, testing approach, adding new cryptographic operations
• Dependencies: Minimizing external dependencies, preferring Node.js built-ins

📚 Educational Focus

Since this is an educational/demonstration project, the instructions guide Copilot to:

• Prioritize clarity and educational value
• Include explanations in the UI where appropriate
• Make results visible and understandable
• Show intermediate steps when helpful for learning

Benefits

With these instructions in place, GitHub Copilot will:

• ✅ Understand the project structure and tech stack immediately
• ✅ Follow consistent coding patterns matching the existing codebase
• ✅ Apply proper security practices for cryptographic code
• ✅ Make appropriate suggestions for new features
• ✅ Maintain the educational purpose of the project

Cryptographic Features Documented

The instructions cover all cryptographic implementations:

• Hash Functions: SHA-256 hashing, salted password hashing
• HMAC: Hash-based Message Authentication Code
• Symmetric Encryption: AES-256 encryption/decryption
• Asymmetric Encryption: RSA encryption/decryption
• Post-Quantum Encryption: Crystals-Kyber (ML-KEM-768) - NIST standardized
• Digital Signatures: RSA-SHA256 message signing and verification

Testing

Verified that:

• ✅ Application starts successfully on port 3000
• ✅ API endpoints respond correctly
• ✅ File structure is properly organized in .github/
• ✅ No unwanted files included in the commit

Resolves #[issue_number]

Original prompt

---

This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #8

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.