Show your work. Explain what techniques you applied. Cite all tools and sources used. A correct answerwithout supporting work may not receive full credit.1. Consider the encryption defined by the following table.PlaintextABABABLet the plaintext probability distribution be P(A)P(k₂) = 1/2, P(ks) = 1/4.(a) Find the ciphertext probability distribution.Key CiphertextDk₁k₁Ek₂Fk₂Dk3Ek3F1/4, P(B) = 3/4 and the key distribution be P(k₁) = 1/4,(b) Find entropy of the plaintext variable, the key variable, and the ciphertext variable.(e) Find the key equivocation.(d) Find a different key distribution that will make the key equivocation less than 0.5.(e) Find a different key distribution that will make the key equivocation greater than you found in question le above.

Answer is explained below stepwise

Let the plaintext probability distribution be P(A) 1/4, P(B) = 3/4 and the key distribution be P(k₁) = 1/4, P(k₂) = 1/2, P(ks) = 1/4. (a) Find the ciphertext probability distribution. (b) Find entropy of the plaintext variable, the key variable, and the ciphertext variable. (e) Find the key equivocation. (d) Find a different key distribution that will make the key equivocation less than 0.5. (e) Find a different key distribution that will make the key equivocation greater than you found in question le above.

Let the plaintext probability distribution be P(A) 1/4, P(B) = 3/4 and the key distribution be P(k₁) = 1/4, P(k₂) = 1/2, P(ks) = 1/4. (a) Find the ciphertext probability distribution. (b) Find entropy of the plaintext variable, the key variable, and the ciphertext variable. (e) Find the key equivocation. (d) Find a different key distribution that will make the key equivocation less than 0.5. (e) Find a different key distribution that will make the key equivocation greater than you found in question le above.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

See similar textbooks

Similar questions

Consider the affine cipher f(p) = 3p+4 (mod 26), where p is the plaintext representation of the character under consideration. For example the plaintext of the letter A is 0, B is 1, C is 2, ... Z is 25. Use this cipher to encrypt the letters I, N, G, R (changing the numbers back to letters at the end.
Show that decryption in a Feistel cipher can be done by applying the encryption algorithm to the ciphertext, with key schedule reversed.
For a block cipher with encryption Ek() and decryption DK(), the equation for the CBC mode of operation is: Cj = EK(Pj e Cj-1). What is the equation for decrypting C?
Let k be the encipherment key for a Caesar cipher. The decipherment key is 26 – k.One of the characteristics of a public key cryptosystem is that the encipherment anddecipherment keys are different. Explain why the Caesar cipher is a secret keycryptosystem, not a public key cryptosystem?
In the Elgamal encryption scheme, Bob's public key is fixed, but Alice uses a fresh random i e {2,...,p – 2}, and hence a fresh random kg, whenever she wants to send Bob a message. What happens if Alice uses the same i for ecrypting multiple messages? Can Trudy recover any meaningful information from the ciphertexts?
Let E'(T,X) be a tweakable block cipher that has already been keyed. Given plaintext P = P1 || P2 || ... || Pn (ie, P is an n-block plaintext). Ci = E'(i, Pi) for i=1..nsum = P1 xor P2 xor ... xor Pntag = E'(0,sum) For simplicity let's say that E'(T,X) = ROTL(X,T+1) (ie, X rotated left T+1 bits. If the block cipher block size is 8 bits and you are encrypting the two byte plaintext 67 89, what ciphertext and tag would be created? Fill in each box as a two-digit hex value. C1____? C2____? tag____?
Suppose that the following ciphertext is received by a person having BIGamal puti- key (71. 7. 32) and private key k = 30: (56, 45) (56, 05) (56, 38) (56, 27) (56, 29) (56, 31) (56, 03) (56, 38) (56, 67) (56. 29) Obtain the plaintext messae
If an encryption function er is identical to the decryption function dg, then the key K is said to be an involutory key. (a) Let K = (a, b) be a key in an affine cipher over Z/nZ. Show that K is an involutory key if and only if a- = a (mod n) and b(a+1) = 0 (mod n).
We want to set up RSA cryptosystem in a network of n users. a. How many prime numbers do we have to generate a key for users? b. Now consider we want to reduce this number by generating a smaller pool of prime numbers and making combinations of two of these primes (for each user we pick up a new pair). How is security of RSA cryptosystem affected?
Alice and Bod have decided to use a symmetric encryption algorithm. They have some assumptions about their messages:- Messages only contain capital letters (i.e. A to Z)- The length of their shared key must be greater than or equal to the length of the plaintext- They assign each letter a number as follows: (A,0), (B,1), (C,2), (D,3),…, (Z,25)Their algorithm combines the key and the message using modular addition. The numerical values of corresponding message and key letters are added together, modulo 26. For example, if the plain text is “HELLO” and the key is “SECRET” then the encrypted message is calculated as following:Since the length of the plaintext is 5, we just need the first 5 letters of the key (i.e. “SECRE”), then for each letter, we should add corresponding letters in both the plaintext and the key modulo 26.Plaintext: H (7) E (4) L (11) L (11) O (14)Key: S (18) E (4) C (2) R (17) E(4)Cipher: Z (25) I (8) N(13) C(2) S (18) Write a program in Python, C/C++ or JavaScript to…