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08 - Vernam cipher

 1. The Vernam cipher is named after its inventor Gilbert Vernam.

  FALSE

  TRUE

 2. The cipher was originally invented to scramble text transmitted by …
vernam_q2.png

  radio broadcast

  teleprinter

  telegram

  email

 3. How was the Vernam cipher key originally fed into the system?

  by tape with punched holes

  by a floppy disk

  via the Internet

  by manual input

 4. The Russian engineer Vladimir Kotelnikov proved the cipher was unbreakable if the key was …

  also encrypted

  truly random and not repeated

  very short

  sufficiently long

 5. The principles were developed into a manual encryption system known as the …

  one time pad

  once said report

  one chance book

  one use cipher

 6. Why is the Vernam cipher not vulnerable to frequency analysis?

  As each plaintext character is transposed by a random number

  As the ciphertext can be transmitted very quickly

  As the length of the key makes it difficult to compute

  As each plaintext character is transposed by a fixed number

 7. The Vernam cipher uses an XOR logical operation. What does this mean?

  The output is false only if both inputs are different

  The output is true only if both inputs are false

  The output is true only if one input is true and the other is false

  The output is true only if both inputs are the same

 8. XOR could also be written as …

  A or B or A and B

  A and B but nor A or B

  A or B but not A and B

  A or B

 9. An algorithm can generate a truly random key number.

  FALSE

  TRUE

 10. Using binary and XOR, how would 10101 appear in ciphertext if the key is 00110?

  11100

  11110

  10011

  10001


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