Sending Signals and Making Messages

Introduction
Public summary: 

A fun talk about how humans have communicated over the years and how we can talk to each other privately in the modern world, with a few simple demonstrations of how the internet works and how to keep messages secret using encryption.

Communications lecture used for CBS 2014 and 2015 and other past CBS years
Useful information
Kit List: 

String telephone (string, 2 plastic cups)

4 boxes or trays, with colour coded names stuck to them
Assorted colours of paper (blue, yellow, green, red) corresponding to box colours
Paper planes (white, blue, yellow, red, green), with enough of the right colours to form the 5x5 image used in the presentation and numbered as in the diagram, and some extra planes of various colours

Plastic toolbox
2 locks/padlocks for toolbox
Torch

Laser pointer (useful, not necessary)
2 demonstrators (possible with one but not as good)
3rd demonstrator as plant in audience (optional)

Packing Away: 

Place all reasonably intact planes in bag, place all small items in toolbox and store together for future use

Explanation
Explanation: 

Summary of Talk

See attached documents for full content and experiment demonstrations

Slide 1 - Cover slide

Slide 2 - Introduction

Slide 3 - Frame problems and goals of communicating, such as fast, reliable delivery over long distances, in a secure manner. The 3rd demonstrator in the audience should be used at this time to demonstrate security problems by stealing a message.

Slide 4 - Historical Perspectives on Communication - Examples of methods used in the past

Slide 5 - Historical Perspectives on Communication 2 - Morse code as an example of sending arbitrary messges quickly, with the Titanic shown as the first occurence of an SOS message sent by Morse code

Slide 6 - Example of Caesar cipher as a simple way to encrypt message and ensure safety, point out such simple methods are quick to brute force solve.

Slide 7 - Demonstration of assymetric key encryption as a way of sending a secure message, using a box and 2 locks, with the front row of the audience as the transmission medium

Slide 8 - The Telephone as a Method of Communication - Demonstrate with string telephone, possibly with audience volunteer

Slide 9 - Problems of One-to-One Communication Lines - Shows the arithmetic progression of lines required

Slide 10 - Problems of One-to-One Communication Lines 2 - Poses question to audience of how many lines 100 connections needs

Slide 11 - Problems of One-to-One Communication Lines 3 - Presents answer, and shows arithmetic sum formula as a quick method of calculation

Slide 12 - Communications Networks - Shows how connections are arranged to allow full connectivity via other nodes

Slide 13 - Demonstration of Sending Messages via Network - Uses colour-coded boxes and paper aeroplanes to demonstrate connectionless switching, using the audience as an analogy to the network

Slide 14 - Demonstration of Packets in Networks to Send Large Messages - Uses colour-coded boxes and paper aeroplanes to demonstrate packet switching networks sending images, using the audience as an analogy to the network

Slide 15 - Interim slide, displayed while previous demonstration is occuring, as a prompt for the audience

Slide 16 - Recap of initial image to assist in reassembly of image, with volunteer help

Slide 17 - Concluding slide, summing up talk and thanking audience, showing CHaOS contact details

Risk Assessment
Date risk assesment last checked: 
Fri, 13/02/2015
Risk assesment checked by: 
vrb23
Date risk assesment double checked: 
Fri, 13/02/2015
Risk assesment double-checked by: 
Miffles
Risk Assessment: 

String Telephone

DESCRIPTION Two plastic cups with holes in base, connected with a string, knotted at ends after passing through holes.
RISKS
  1. Trip hazard of string
ACTION TO BE TAKEN TO MINIMISE RISKS
  1. Ensure string telephone is kept in storage box when not in use, with string neatly coiled inside a cup. When in use, ensure no audience members are near, unless using it.
ACTION TO BE TAKEN IN THE EVENT OF AN ACCIDENT

    Call First Aider

Assymetric Key Encryption with Toolbox and Locks
DESCRIPTION A box is locked with a lock, passed to a second demonstrator via the audience, locked again, then returned. The original lock is removed, then passed back, allowing the second lock to be removed, passig a message securely with no exchange of keys.
RISKS
  1. Audience may drop box
  2. Keys and locks are small and are swallowing hazard
ACTION TO BE TAKEN TO MINIMISE RISKS
  1. Boxes are selected so they are light plastic, with no sharp edges
  2. Keys and locks are strictly kept in the possession of demonstrators, except when securely attached to the box
ACTION TO BE TAKEN IN THE EVENT OF AN ACCIDENT
  1. Call a first aider.

Paper planes messages and sending pictures

DESCRIPTION Messages are sent to colour-coded boxes, by throwing paper aeroplanes to the audience and saking them to pass the message to its eventual location. A picture is 'transmitted' by the same method, using numbered aeroplanes to reconstruct the image in the correct order.
RISKS
  1. Risk of paper aeroplanes striking audience, particularly eyes.
ACTION TO BE TAKEN TO MINIMISE RISKS
  1. Only throw planes gently, at angles above the audience, to avoid direct collisions. Warn the audience to be aware of the risk during this activity, and to throw gently as well.
ACTION TO BE TAKEN IN THE EVENT OF AN ACCIDENT
  1. In the unlikely event of injury, call First Aider.
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