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Are the Androids Dreaming Yet?

Codes
Everyone has played with some sort of secret code as a child – the Aggy Waggy game, passing notes written in invisible ink made from lemon juice, or perhaps a simple cypher. If I want to send you a secret message, I can use a substitution code. Let’s see how good a code breaker you are. Can you decode this?

Gdkkn Qdzcdq

It’s really easy. You might guess the message from the pattern of letters and your knowledge of my writing style. There are a couple of interesting patterns to note: the 3rd and 4th letter of the first word are the same and the first and last letter of the second word are the same. As a test I gave this code to my wife and my eight-year-old daughter to see how long it took them to decode… Less than a minute for my wife – a linguist. We will come back to my daughter shortly!

Enigma Machine

Roman Emperors used this sort of simple code to secure their messages, but modern codes have to be a great deal more sophisticated. Let us use a progressive cipher where we vary the substitution using a secret word. Take the name of my dog and write it down repeatedly next to the letters of the message you want to keep secret. Now translate all the letters in the message and the code into numbers ‘a’ = 1, ‘b’ = 2 and so on. Then add the letters of my dog’s name to the letters of the message one at a time. If I get to 26 (‘z’) just wrap around to ‘a’ and carry on. This is called modulo arithmetic. This coding scheme will translate ‘l’ to ‘a’ the first time but ‘l’ to ‘c’ the second making it much harder for a linguist to see any pattern.

hello reader can you read this code
georgegeorgegeorgegeorgegeorgegeorge

Gives

ojacveyjpvlwghpegcvzoilfkehzpxghcvle

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