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Quantum Computing for Computer Scientists

Noson S. Yanofsky, Mirco A. Mannucci

Chapter 9

Cryptography - all with Video Answers

Educators

Section 1

Classical Cryptography

01:48

Problem 1

Does Equation (9.3) imply that $E N C\left(-, K_E\right)$ and $D E C\left(-, K_D\right)$ are a pair of bijective functions that are inverse to each other?

Mohamed Mohamed
Mohamed Mohamed
Numerade Educator
07:33

Problem 2

Decipher the following message "JNTGMNF VKRIMHZKTIAR BL YNG."

Sirat Shah
Sirat Shah
Numerade Educator
07:35

Problem 3

Find a friend and flip a coin to get an encryption key $K$. Then use $K$ to send a message. See if it works.

Christine Anacker
Christine Anacker
Numerade Educator

Problem 4

Suppose Alice generates only one pad key $K$, and uses it to encrypt two messages $T_1$ and $T_2$ (we are assuming they have exactly the same length). Show that by intercepting $E_1$ and $E_2$, Eve can get $T_1 \oplus T_2$ and hence is closer to the original text.

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Problem 5

Suppose Alice and Bob communicate using some kind of public-key protocol. Alice has a pair of keys (one public, one private), and so does Bob. Devise a way in which Alice and Bob can communicate simultaneously while authenticating their messages.

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