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

Distinguish between passive and active attacks, Problem (a) Distinguis...

Problem (a) Distinguish between passive and active attacks. (b) Give two reasons why it is important to organise security awareness programs for users. (c) Describe how

Network intrusion system, In this work a network intrusion system (package)...

In this work a network intrusion system (package) must implement based on high interaction honeypots. There are two honeypots with different platforms (ubuntu and windows server 20

Encryption, How safe is the encryption of virtual private networks?

How safe is the encryption of virtual private networks?

Wireless sensor networks, The project will be involving a design and a repo...

The project will be involving a design and a report of which explain the simulation and how it functions. The aim of the project is to help the administrators and staff at the war

Security policies, implementing password policy in organisation

implementing password policy in organisation

Rsa block and vernam stream ciphers, RSA Block and Vernam Stream Ciphers ...

RSA Block and Vernam Stream Ciphers This assignment involves writing two small Python scripts and a report. Before you start you must download the ?le summarysheets.zip from th

Extended euclidean algorithm, (a) Using the extended Euclidean algorithm, ...

(a) Using the extended Euclidean algorithm, find the multiplicative inverse of 504 mod 67. (b) Decrypt the following ciphertext, which has been encrypted using Caesar cipher:

Computer fundamentals, Ask You have been asked by a new client to assist i...

Ask You have been asked by a new client to assist in setting up a new computer for her coffee shop. She has just purchased the newest Apple computer from an online site. Should wou

Arp responses, ARP RESPONSES Let's search out how does a computer know...

ARP RESPONSES Let's search out how does a computer know whether an incoming frame have an ARP message. The type field in the frame header defines that the frame contain an ARP

Pgp encryption, Produce a short report of your experiences in installing an...

Produce a short report of your experiences in installing and using PGP. The report should be written in the form of a journal that contains at least the following items: A de

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