Encryption
This lesson and next lesson we are going to explore
encryption in more detail:
Task 1
Make sure that you have the following definition
A key is used to encrypt
plain text into meaningless cipher text, the same key is used to
decrypt the data back into its original form. Only someone who knows the key
can decrypt the cipher. If you don’t have the key you need to crack the code.
Task 2
Watch the following film about the Enigma machine. Afterwards in your own words try to write a
summary of how it works.
Use the YouTube video ‘158,962,555,217,826,360,000’ to
introduce the Enigma machine: http://www.youtube.com/watch?v=G2_Q9FoD-oQ
Task 3
Introduce the Codebreaker challenge: http://turinggame.sciencemuseum.org.uk. Pupils to work in pairs
to tackle the challenge.
Homework: Last week you created a Caesar Cipher. Your task this week is to create your own
cipher. You will need to show how it works. It must be secure but also you must show how
to translate the enciphered text back into plain text. This can be done in
Post your answers to
the blog by Thursday 5th February at 5.00pm
Task 4
First
of all let’s look at the following video about the Caesar Cipher. Make sure that you have a short description
of how the Caesar Cipher works.
Try to send some messages to
your partner using the Caesar Cipher
TASK 5
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Use a
Caesar cipher to decode and encode these messages.
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Plain text
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Shift
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Encrypted text
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THE ENIGMA
MACHINE WAS INVENTED BY THE GERMANS
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+3
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COLOSSUS
WAS THE WORLD’S FIRST DIGITAL COMPUTER
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+4
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+5
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YMJ
HFJXFW HNUMJW NX FS JCFRUQJ TK WTRFS NSLJSZNYD
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-3
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QEB
HBV FP EFAABK RKABO QEB CILTBO MLQ
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Task 6
With a partner, produce a step-by-step guide to using a
Caesar cipher to produce an encoded
message.
Task 7
Produce a step-by-step guide to decrypting messages that
have been encoded using a Caesar cipher.
