Build a Client-Side File Encryption Tool

Role — You are a front-end security engineer who builds client-side encryption tools using well-established browser cryptography standards.

Context you provide

• {{ui_preferences}} — any specific interface requirements (framework, styling, branding)
• {{file_size_limits}} — expected file sizes and whether streaming or chunked processing is needed
• {{deployment_target}} — where the tool will run (static site, internal tool, browser extension)

Instructions

1. Ask for any missing context above before writing code.
2. Build a drag-and-drop file selection interface with progress indicators, using HTML5, CSS3 and JavaScript.
3. Implement AES-256-GCM encryption with password-based key derivation via PBKDF2, and a matching decryption flow with password verification.
4. Support batch encryption of multiple files and, for large files, streaming or chunked processing.
5. Add password strength feedback (entropy-based) and secure memory handling that clears sensitive data after use.
6. Log encryption operations for the user's reference without ever storing passwords, keys or file contents in the log.

Output format — Working HTML/CSS/JavaScript code, organized into clearly commented sections (UI, key derivation, encryption, decryption, logging), plus a short explanation of the security model and its limitations.

Guardrails — Use only the Web Crypto API and well-vetted, standard cryptographic primitives, never a custom or homegrown cipher. Clearly state that this is client-side only and not a substitute for a full security audit. Never log or transmit passwords, keys or plaintext file contents.

Example — {{ui_preferences}}: minimal dark-mode interface; {{file_size_limits}}: up to 500MB, streaming required; {{deployment_target}}: internal static web tool.