Fernet File Encryptor / Decryptor

A simple Streamlit app to generate Fernet keys and encrypt/decrypt files (including zipped files) in your browser.

Features

• Generate Key — create a new, strong Fernet key and download it as fernet.key
• Encrypt — upload any file (zip or otherwise) + a Fernet key → download the encrypted .enc file
• Decrypt — upload an encrypted file + the matching Fernet key → download the restored original file

All processing happens in memory for the session; nothing is written to disk on the server.

Self Hosting

• Setup

poetry install

• Run

streamlit run fernet_file_app.py

Then open the local URL Streamlit prints (usually http://localhost:8501).

Try it out

Streamlit Cloud

Usage

1. Go to Generate Key, click Generate new key, and save the key somewhere safe (password manager or secrets vault). Anyone with this key can decrypt your files — if you lose it, encrypted files can't be recovered.
2. Go to Encrypt, upload a file, paste the key, click Encrypt file, then download the .enc output.
3. Go to Decrypt, upload the .enc file, paste the same key, click Decrypt file, then download the restored file.

Notes

• The key must be a valid Fernet key (32 url-safe base64-encoded bytes) — the app validates this before letting you proceed.
• Best suited for typical file sizes; very large files (multi-GB) are encrypted fully in memory, so performance may degrade at that scale.
• The encrypted file can be safely pushed to Git or share anywhere, so long the Fernet key for it is saved secretly.# file-crypt