Beyond trivial
BBC website:

Information typed on a wireless keyboard can be easily intercepted, a cybersecurity research firm has warned. San Francisco-based Bastille said keyboards transmitted what was being typed in "clear text", making it possible for attackers to listen in on from up to 76m (250ft) away. The firm said affected keyboards could not be updated and should be replaced.

Jesus. This is not news. Wireless keyboards have been around for 30 years. This characteristic has been known all along. Even the word known is unnecessary.


A device emits an RF signal when you push a button.

Therefore the RF signal can be received and recorded.

This is called "radio". It was first invented by Fessenden and Marconi.



As for the clear-text, anyone who knows a teeeeensy bit about cryptography can figure that out.



Each button must produce a unique and constant bit pattern.

This is called "telegraphy". It was first invented by Wheatstone and Morse.



Changing the bit pattern in a constant way (eg always substitute ASCII 8 for ASCII E) is no better than clear text, because a competent crypt expert can determine the mapping easily and use it thereafter.



This is called the "Caesar cipher." It was first invented by Mr Julius A. Caesar.



Truly enciphering a message requires modifying the bit patterns in a time-varying way that is known to both sender and receiver. The first E becomes 8, the second E becomes P, or whatever. Each keystroke moves the modifier ahead by one step.

You can do this with a message written on a piece of paper, and you can do this in a rigidly controlled protocol. In those situations you know for sure what FIRST means, so the receiver knows how to sync the modifier with the coded text. (Other encryption methods such as jumbling or hashing also require knowing where the message or sentence or block starts and ends. There's no point in doing one letter at a time.)

You can't do this with a wireless keyboard,

because there's no firm way to decide what FIRST means. First character of the day? First of this message? First in the lifetime of the computer? Use the system time in milliseconds to set the modifier? Some of these are intrinsically meaningless. The system time method is screwed when the wireless keyboard loses contact for a moment, which happens often. You'd have to make both keyboard and computer subservient to an external synchronizer. If you're deep enough in secret circles to develop a system like that, you already know that it's just a whole lot easier to use a wired keyboard or a manual typewriter or paper and pencil. Or you're protected by Faraday cages and constant countersurveillance.
  ¶ 3:50 AM