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

Wan architecture and wan service, MegaCorp INC. is a large manufacturing f...

MegaCorp INC. is a large manufacturing firm that operates 5 factories in Dallas, 4  factories in Los Angeles, and 5 factories in Albany, New York.  It operates a tightly  connected

Network management system, Question (a) Draw a typical hybrid star-rin...

Question (a) Draw a typical hybrid star-ring topology paying attention to how the clients and switching hubs are connected. (b) State 3 main differences between a router

Short term scheduler, Short term Scheduler function , also shown as a disp...

Short term Scheduler function , also shown as a dispatcher runs most frequently, and creates the finest-grained decision of which program could run next. This scheduler is called

Define repeater, Repeater known as regenerator ; it is an electronic mac...

Repeater known as regenerator ; it is an electronic machine that performs only at physical layer. It gets the signal in the network before it becomes loss or weak, recreates the

Compare and contrast data encryption standard, Problem (a) Using Vigen...

Problem (a) Using Vigenère cipher and given the key abc, find the ciphertext for the message: simplicity Only the 26 lower-case alphabetical characters are used in messa

Selecting a risk control strategy, Selecting a Risk Control Strategy Risk...

Selecting a Risk Control Strategy Risk controls involve selecting one of the 4 risk control strategies for every vulnerability. The flowchart is shown in the figure given below

Bus topology, BUS TOPOLOGY In a bus topology all devices are attached ...

BUS TOPOLOGY In a bus topology all devices are attached to a single long cable and any device can send data to any other device. For this function, coordination is needed to d

Determine the round trip time, QUESTION a) Determine the RTT (round tr...

QUESTION a) Determine the RTT (round trip time) between a client requesting a web page of 1024 bytes in size from an internal web server on a 100 Base-T Ethernet. Consider a o

Develop a tcp-based client-server socket program, Develop a TCP-based clien...

Develop a TCP-based client-server socket program for transferring a large message. The message transmitted from the client to server is read from a large file (size is about 30000

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