Find the possible deciphering transformations, Computer Network Security

Assignment Help:

Question:

(a) A string of ciphertext was enciphered using an a±ne transformation of single letters in a 28-letter alphabet consisting of A to Z, a blank and a?, where A to Z have numerical equivalents 0 to 25, blank=26, ?=27. A frequency analysis reveals that the the first, second and third most common letters of this ciphertext are B, ? and I, respectively. Suppose that the first and second most common letters in an English language text written in this 28-letter alphabet are ` '(blank) and E, respectively.

(i) Find the possible deciphering transformations.

(ii) Using the fact that T, is the third most common letter in the English language (of our 28 letters), find the right deciphering transformation.

(b) The ciphertext

¡GSTMTSI XJMUIGHRFKYMV

was generated using a 2£2 enciphering matrix with a 29¡letter alphabet, where A to Z have numerical equivalents 0 to 25, blank=26, !=27, and ¡ = 28. Given that the last five letters of the plaintext are A¡ONE, determine the complete plaintext.


Related Discussions:- Find the possible deciphering transformations

Explain how inter-vlan communication, QUESTION a) A switch basically ...

QUESTION a) A switch basically operates by forwarding frames from one part of the network to another, based on MAC address. Describe the three types of switching namely store

Identified issues in networks, The "Big Red Rocks" (BRR) mining company is ...

The "Big Red Rocks" (BRR) mining company is based and operates in Western Australia. They are primarily an iron ore miner, but they also produce electricity through tidal power to

Describe the use of control channels in gsm network, Problem 1: What is...

Problem 1: What is the function of AUC in the GSM architecture? Explanation of HLR(AUC) Architecture of GSM Problem 2: Show the layered architecture of t

Public key cryptosystem based on rsa technology, Problem: (a) What is ...

Problem: (a) What is the minimum length of a password that could be considered to be "strong" in the context of today's computing power? (b) The security of a PIN system,

Plain-text using play-fair encryption, What is one-time pad for encryp...

What is one-time pad for encryption?  Describe how it offers both Confusion and Diffusion. Using the letter encoding discussed in class (along with one-time

Star topology, STAR TOPOLOGY In this topology, all devices are attache...

STAR TOPOLOGY In this topology, all devices are attached to a central point, which is sometimes known as the "Hub" as given in the diagram below.   Figure: An ideal

Application layer protocol, Problem a) Give the destination IP address, up...

Problem a) Give the destination IP address, upper layer protocol, TTL in decimal and header checksum in hexadecimal; the source port number and the destination port number in deci

Estimate the average throughput, Question (a) Estimate the average thr...

Question (a) Estimate the average throughput between two hosts given that the RTT for a 100 bytes ICMP request-reply is 1 millisecond and that for a 1500 bytes is 2 millisecon

Introduction to cryptography, INTRODUCTION TO CRYPTOGRAPHY Cryptography...

INTRODUCTION TO CRYPTOGRAPHY Cryptography The word cryptography is derived from Greek words kryptos, which means hidden and graphein, meaning to write, this is the process of

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd