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03 - What is encryption?

 1. Why might you want to encrypt a document?

  To prevent unauthorised people from reading it

  To speed up its transfer

  To reduce its size

  To stop it being opened by an unauthorised person

 2. Encryption was originally invented to protect data on electronic computers.

  FALSE

  TRUE

 3. In the early 20th century, telegrams could be electro-mechanically encrypted.

  TRUE

  FALSE

 4. How did weak encryption lead to the entry of the USA into the First World War?
encryption_q4.jpg

  A letter using a simple substitution cipher was intercepted in the mail

  A carrier pidgeon carrying secret plans was captured in France

  An encrypted German telegram to Mexico was intercepted and decrypted by the UK

  An ambassador left a floppy disk on a train and the data was not encrypted

 5. In 2007 a UK Government department lost two CD-ROMs of unencrypted data in the post. 
The personal details of how many individuals were potentially compromised?

  15 million

  1 million

  25 million

  10 million

 6. Substitution ciphers are vulnerable to …

  rotation archiving

  frequency analysis

  notation charting

  wave analytics

 7. What did Leon Battista Alberti devise in the 15th century?

  The Caesar cipher

  RSA encryption

  Morse code

  The polyalphabetic cipher

 8. If the length of the key can be discovered, even a polyalphabetic cipher can be vulnerable to …

  frequency analysis

  notation charting

  wave analytics

  rotation archiving

 9. How did the Enigma machine used in World War Two encrypt messages?
encryption_q9.jpg

  By mechanical rotors that moved to form different electrical circuits

  By rotation archiving

  By wave analytics

  By a ticker tape fed key

 10. Today public key algorithms are usually based on …

  computational complexity of hard problems

  ticker tape problem solving

  rotation archiving

  analytics of the Big O prototype


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