🔒 SecureChat — Free TV & Film Prop

A portable, peer-to-peer encrypted chat application designed for use as a screen prop in TV and film productions. Fully functional, fully customisable, completely free to use.

Inspired by the aesthetic of Mr. & Mrs. Smith (2024, Prime Video — Donald Glover, Maya Erskine).

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Amber Terminal	Clean Light

Real screenshots of the running app. The red-bordered bubble is a self-destruct message. The conversations are fictional.

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What it is

A real, working encrypted chat interface — not a mockup, not a loop. Two devices, one USB stick, actual messages sending and receiving in real time. Built for productions that need something that looks authentic because it is authentic.

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Encryption

• NaCl Box — X25519 key exchange + XSalsa20-Poly1305 authenticated encryption (libsodium via PyNaCl)
• Messages encrypted before leaving the machine
• Peer-to-peer — no server, no cloud, no third-party dependency
• Keys live in ~/.securechat/keypair.json

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Features

Themes — three built-in visual styles

Theme	Aesthetic	Button
Dark Teal	Black + teal, monospace — Mr. & Mrs. Smith style	TRANSMIT
Amber Terminal	Black + amber, thick borders — government/classified ops	TRANSMIT
Clean Light	White + dark bubbles — modern, civilian, everyday	Send

Switch theme from the ⚙ Appearance menu, or via command line:

python securechat.py --server --theme "Amber Terminal"
python securechat.py --server --theme "Clean Light"
python securechat.py --server --theme "Dark Teal"

Scheduled Messages

Set a message to send automatically at a specific date and time — DD/MM/YYYY format.

• One-time — fires once at the scheduled time
• Annual recurring — fires every year on the same date, forever (perfect for birthdays, anniversaries, plot devices)
• Accessible via the ⏰ Schedule a Message button in the sidebar

Self-Destruct Messages

Mark any message — live or scheduled — as self-destruct. The recipient sees it with a red border and a countdown label. Five seconds after it appears on their screen, it is automatically deleted from their local database.

Toggle the 💥 checkbox next to the input field before sending.

Fully Customisable Appearance

From the ⚙ Appearance menu:

• Background colour, chat background, accent colour
• Incoming and outgoing bubble colours — separately
• Incoming and outgoing text colours — separately
• Font family and size
• Background image (JPG or PNG)
• Display name

Local Chat Log

All messages stored in a local SQLite database at ~/.securechat/messages.db. No data leaves the machine except the encrypted message itself.

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Where it runs

SecureChat is a Python desktop app (PyQt5), so it runs wherever Python and Qt do.

System	Works?	Notes
macOS 10.15 Catalina	✅	The original target
macOS 11 and later (Big Sur to Sequoia), Intel and Apple Silicon	✅	Runs natively on both chips
Linux (Ubuntu, Debian, Fedora…)	✅
Windows 10 / 11	✅
Windows 7 / 8.1	⚠️	Use Python 3.8, the last version that supports them, and build the .exe on that machine. An .exe built on Windows 10 with a newer Python won't start on Windows 7.
Android / iPhone	❌	Desktop only for now. A phone can scan the pairing QR code, but can't run the chat itself.

On Catalina: if the optional OpenCV install (for reading QR photos) fails, pin an older release: pip install "opencv-python-headless<4.9". Everything else installs as normal.

Setup

pip install -r requirements.txt

Run

Server (the person hosting):

python securechat.py --server

Client (the person connecting):

python securechat.py --client --host 192.168.1.42

No arguments — the app asks you on launch.

Exchange Keys

The quick way: copy and paste

1. Click "Copy My Public Key" — send to your chat partner (it's public, not secret)
2. They click "+ Add Peer Key" and paste yours in
3. Done — all messages now encrypted end-to-end

The cinematic way: scan a QR code

Your public key can be shown as a QR code, in the terminal or in the app. Point a phone at it and the keys change hands in a second, which looks every bit as good on camera as it sounds.

python securechat.py --show-key

That prints your key as a big QR code, black on white so it scans in light and dark terminals alike. Then your partner can do any of these:

They have…	They do…
A phone	Scan it with the camera. It reads a securechat:// link; send it to their computer and paste it into "+ Add Peer Key". The name fills itself in.
A photo or screenshot of it	Click "+ Add Peer from QR" and pick the image, or run python securechat.py --add-peer-qr photo.jpg
The link as text	python securechat.py --add-peer "securechat://peer?name=…&key=…"

In the app, "Show My Key as QR" puts the same code on screen.

The QR holds only your public key and display name, so it's safe to show, film or post. Your private key never leaves your machine. Reading QR codes from photos needs OpenCV (pip install opencv-python-headless); everything else works without it.

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Build a standalone executable (USB stick ready)

pip install pyinstaller
pyinstaller --onefile --windowed securechat.py

Output in dist/ — a single file that runs on Windows, Mac, or Linux without Python installed. Put it on a USB stick and it runs on any machine by double-clicking.

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Chat over the internet

Use Tailscale (free, takes two minutes to set up) — both people install it, then use the Tailscale IP as the host address. No port forwarding required.

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Wipe everything

rm -rf ~/.securechat/

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Licence

Free to use in:

• Independent films
• Short films
• Student films
• TV series and episodic productions
• Documentaries
• Theatre and live performance
• Music videos
• Anything with Stanley Tucci in it
• Anything made by Christina Heartmill | Director & Filmmaker

Not free for:

• Commercials and advertising
• Marvel productions (any studio, any universe)
• Any production with a total budget exceeding €2,000,000

If your production falls into the not-free category, get in touch. We can work something out.

Credit

Not required but genuinely appreciated: & "A box of Donuts"

Chat interface prop: SecureChat — github.com/lolo737/securechat

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Read more

Medium article: [I Made a Free Prop for TV Productions — Inspired by Mr. & Mrs. Smith](https://medium.com

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About

Built by lolo737. Customable is chat for use in TV series as a prop — and it works.