03 - What is encryption?

 1. Why might you want to encrypt a document?

  To stop it being opened by an unauthorised person

  To prevent unauthorised people from reading it

  To reduce its size

  To speed up its transfer

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



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



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

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

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

  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

 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 …

  wave analytics

  rotation archiving

  frequency analysis

  notation charting

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

  Morse code

  The Caesar cipher

  The polyalphabetic cipher

  RSA encryption

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

  notation charting

  wave analytics

  rotation archiving

  frequency analysis

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

  By rotation archiving

  By mechanical rotors that moved to form different electrical circuits

  By wave analytics

  By a ticker tape fed key

 10. Today public key algorithms are usually based on …

  rotation archiving

  ticker tape problem solving

  computational complexity of hard problems

  analytics of the Big O prototype