CRYPTOGRAPHY TRIVIA

The Game 8 groups of 2 5 rounds

Basic Definitions Substitution Cryptosystems Math Tricky Questions Comparing Cryptosystems

10 questions per round Each question is worth 1 point

Basic Definitions1. Alice and Bob should at some point have

access to a ________ mode of communication.2. Cryptography is only needed when a message

is both _______ and ________.4. To determine how difficult a cryptosystem is

to break, we measure its ________.5. To determine how quickly a cryptosystem

operates, we measure its ________.

Basic Definitions6. _______ is the science of keeping information

secure even though it is transmitted through an insecure medium.

7. _______ is the science of breaking ciphers.8. A _______ is a matching between two different

alphabets.9. To break a cipher means to determine the

______.10. A cryptosystem is made up of five parts:

plaintext space, ciphertext space, encryption function, decryption function, and __________.

Substitution Cryptosystems1. A substitution cipher uses this to represent its

key.2. A rotation cipher uses this to represent its key.3. An affine cipher uses this to represent its key.4. How many possible keys does a substitution

cipher on have?5. How many possible keys does a rotation

cipher on have?

Substitution Cryptosystems6. How many possible keys does an affine cipher

on have?7. Encrypt using a rotation cipher over with .8. Encrypt using an affine cipher over with 9. Cipher X consists of a rotation, and then an

affine cipher. What type of cipher is X?10. Cipher Y is a substitution cipher over . Cipher

consists of applying Y twenty-four times. What type of cipher is X? Be as specific as possible.

Math1. Find in .2. Find in .3. Find in .4. Find in .5. Find .6. Solve for and .7. Solve the pair and for and .8. For what is invertible in ?9. Find the prime factorization of 142.10. Find in .

Tricky Questions1. Which of these is a faster growth rate: or ?2. Which of these is a faster growth rate: or ?3. Approximately how many primes are there

between 100,000 and 1,000,000?4. Find a rotation cipher with more keys than a

substitution cipher.5. What is the maximum number of solutions

that can have over . ( are constants, is the variable)

Tricky Questions6. A substitution cipher over has a key sorted by

plaintext. During decryption, how many table-lookups are required in the worst case?

7. A substitution cipher over has a key sorted by plaintext. 4 different characters are encrypted. How many table-lookups are required in the worst case?

8. How many possible Vigenere ciphers over are there that can encrypt exactly 3 characters?

9. A one-time-pad is used on a 5 character message. Oscar figured out the keys, but not the order. In the worst case, how many guesses must be try before deciphering the message?

10. How many factors does 1,000,000 have?

Comparing Cryptosystems1. Among Rotation, Affine, and Autokey, which is

most resistant to a known-plaintext attack? 2. Among Affine, Autokey, and Vigenere, which

can encrypt the fastest?3. Among Affine, Autokey, and Vigenere, which

can decrypt the fastest?4. Which has a larger keyspace? Affine over or

Vigenere over ? 5. Which has a larger keysize? Substitution over

or rotation over

Comparing Cryptosystems6. Which is more secure? Affine or a Vigenere

ciphers?7. Which is more secure? Vigenere or Hill

ciphers?8. Could a computer with 4 processors perform

200 Rotation encryptions or 100 Autokey encryptions faster?

9. Could a computer with 4 processors perform 200 Rotation encryptions or 100 Affine encryptions faster?

10. Which has a larger keyspace? Hill over or Vigenere over ?

CRYPTOGRAPHY TRIVIAThe End

Reference Information Created in the summer of 2013 by Dr.

Jeffrey Beyerl for use in a cryptography class.

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