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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

  email

  telegram

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

  via the Internet

  by tape with punched holes

  by manual input

  by a floppy disk

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

  sufficiently long

  also encrypted

  very short

  truly random and not repeated

 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 fixed number

  As each plaintext character is transposed by a random number

  As the length of the key makes it difficult to compute

  As the ciphertext can be transmitted very quickly

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

  The output is true only if both inputs are false

  The output is true only if both inputs are the same

  The output is false only if both inputs are different

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

 8. XOR could also be written as …

  A or B or A and B

  A or B but not A and B

  A and B but nor A or 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?

  10001

  11100

  10011

  11110


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