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03 - What is encryption?

 1. Why might you want to encrypt a document?

  To speed up its transfer

  To stop it being opened by an unauthorised person

  To reduce its size

  To prevent unauthorised people from reading it

 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

  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

  A carrier pidgeon carrying secret plans was captured in France

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

 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?

  25 million

  15 million

  1 million

  10 million

 6. Substitution ciphers are vulnerable to …

  frequency analysis

  wave analytics

  notation charting

  rotation archiving

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

  Morse code

  RSA encryption

  The Caesar cipher

  The polyalphabetic cipher

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

  notation charting

  rotation archiving

  frequency analysis

  wave analytics

 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 wave analytics

  By rotation archiving

  By a ticker tape fed key

 10. Today public key algorithms are usually based on …

  ticker tape problem solving

  rotation archiving

  computational complexity of hard problems

  analytics of the Big O prototype


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