Overview
SEP for Web is a single‑file, client‑side encryption tool. Open sep.html in a modern browser to encrypt or decrypt files, generate and use keyfiles, create lockers (encrypted containers), run text encryption, and simulate secure file deletion. Nothing is uploaded, everything stays on your device.
Features
- Encrypt/Decrypt files with a password or a keyfile
- Create and unlock encrypted lockers
- Text encryption utility
- Cross‑platform compatibility (works on any modern browser)
- Offline‑first: single HTML file, no network required
Security model
- AES‑GCM with 256‑bit keys
- PBKDF2‑SHA‑256 key derivation (passwords: 100,000 iterations)
- Keyfiles derive keys with 10,000 iterations (reduced from passwords due to high entropy)
- Per‑file random salt and IV
Using the app
- Open sep.html in your browser.
- Choose a tab: Encrypt, Decrypt, Keyfile Tools, String Crypto, or Lockers.
- Follow the inputs on screen. Progress and notifications appear in the UI.
Shortcuts
- Ctrl + 1…5: Switch tabs
- Ctrl + Enter: Run primary action in current tab
File formats
- .sep — encrypted single files
- .locker — encrypted multi‑file container with embedded manifest
- .key — binary keyfile generated by the app
Password strength
The app provides a basic strength meter. Weak passwords are allowed but discouraged, you may be prompted to confirm before continuing.
Important warnings
- All processing is local. There is no account or recovery mechanism. Losing a password or keyfile means permanent loss of access.
- There is no rate limiting, a copied encrypted file can be attacked offline. Choose strong passwords or keyfiles.
- Browser‑based encryption has inherent limitations - see the README for details on the security model.
- University research project disclaimer, no guarantees are provided about the implementation. Keep independent backups.
Tips
- Prefer keyfiles for high‑entropy secrets.
- Store keyfiles separately from encrypted data.
- Consider printing or recording recovery hints in a safe place (not the password itself).
Future Ambitions
- Built‑in Password Library
- Password manager integrations (e.g., Bitwarden)