Feb 1, we use pad 1, Feb 2, we use pad 2, etc.

It's really simple. We can do it on paper with a pencil.

This is what scares governments.

The difficult part is distributing the pads and ensuring that no one else has seen them.

What I did several years ago is coordinate pads between phones by hand. A pretty-dense QR code can pass something like 1400 bytes. Two people who see each other regularly could do this. Long-distance arrangements take a bit more thought.

That doesn't work. What if someone intercepts and/or spoofs messages?