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Cryptography Trivia

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 Definitions.

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Cryptography Trivia

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  1. Cryptography Trivia

  2. 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

  3. Basic Definitions • Alice and Bob should at some point have access to a ________ mode of communication. • Cryptography is only needed when a message is both _______ and ________. • To determine how difficult a cryptosystem is to break, we measure its ________. • To determine how quickly a cryptosystem operates, we measure its ________.

  4. Basic Definitions • _______ is the science of keeping information secure even though it is transmitted through an insecure medium. • _______ is the science of breaking ciphers. • A _______ is a matching between two different alphabets. • To break a cipher means to determine the ______. • A cryptosystem is made up of five parts: plaintext space, ciphertext space, encryption function, decryption function, and __________.

  5. Substitution Cryptosystems • A substitution cipher uses this to represent its key. • A rotation cipher uses this to represent its key. • An affine cipher uses this to represent its key. • How many possible keys does a substitution cipher on have? • How many possible keys does a rotation cipher on have?

  6. Substitution Cryptosystems • How many possible keys does an affine cipher on have? • Encrypt using a rotation cipher over with . • Encrypt using an affine cipher over with • Cipher X consists of a rotation, and then an affine cipher. What type of cipher is X? • 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.

  7. Math • Find in . • Find in . • Find in . • Find in . • Find . • Solve for and . • Solve the pair and for and . • For what is invertible in ? • Find the prime factorization of 142. • Find in .

  8. Tricky Questions • Which of these is a faster growth rate: or ? • Which of these is a faster growth rate: or ? • Approximately how many primes are there between 100,000 and 1,000,000? • Find a rotation cipher with more keys than a substitution cipher. • What is the maximum number of solutions that can have over . ( are constants, is the variable)

  9. Tricky Questions • A substitution cipher over has a key sorted by plaintext. During decryption, how many table-lookups are required in the worst case? • 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? • How many possible Vigenere ciphers over are there that can encrypt exactly 3 characters? • 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? • How many factors does 1,000,000 have?

  10. Comparing Cryptosystems • Among Rotation, Affine, and Autokey, which is most resistant to a known-plaintext attack? • Among Affine, Autokey, and Vigenere, which can encrypt the fastest? • Among Affine, Autokey, and Vigenere, which can decrypt the fastest? • Which has a larger keyspace? Affine over or Vigenere over ? • Which has a larger keysize? Substitution over or rotation over

  11. Comparing Cryptosystems • Which is more secure? Affine or a Vigenere ciphers? • Which is more secure? Vigenere or Hill ciphers? • Could a computer with 4 processors perform 200 Rotation encryptions or 100 Autokey encryptions faster? • Could a computer with 4 processors perform 200 Rotation encryptions or 100 Affine encryptions faster? • Which has a larger keyspace? Hill over or Vigenere over ?

  12. Cryptography Trivia The End

  13. Reference Information • Created in the summer of 2013 by Dr. Jeffrey Beyerl for use in a cryptography class. • This is just a vanilla PowerPoint, but of course like anything you download from the internet: use at your own risk.

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