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

Security services, (a) Mention the five main security services. (b) What...

(a) Mention the five main security services. (b) What is a passive attack? Give an example of passive attack? (c) What four types of active attacks and mention their respecti

Pseudonymous remailers and cypherpunk remailers, Problem (a) As a fore...

Problem (a) As a forensic investigator, you are needed to trace the source of an email. It is suspected that the email header has been forged. Show how you would proceed to

Location to e-mail messages are saved, In the e-mail system, where the e-ma...

In the e-mail system, where the e-mail messages are saved and why? E-mail messages are saved in user’s private electronic mailbox. A mailbox refers to a local/domestic hard drive c

Information and network security, Information and Network Security Part ...

Information and Network Security Part 1- Recovery of an encrypted `word' using a forward search attack. Complete and correct summary for part 1. Adequately commented, clea

What type of rfid tag is more appropriate for ws-pass, Consider the followi...

Consider the following case study: In order to avoid criticisms of their existing manned road-toll payment system on its private road, WS-Pass has decided to adopt an automated

Function of key secrecy and algorithm secrecy in security, What is the func...

What is the function of key secrecy and algorithm secrecy in security?  Algorithm Secrecy is explained as follows: ‘Algorithm secrecy’ is a method of keeping an algorithm

Find the services implemented on your computer, Question: (a) Which typ...

Question: (a) Which type of attacker represents the most likely and most damaging risk to your network? (b) What is the basic reason that social engineering attacks succeed?

Principles of information security, The key concepts and frameworks covered...

The key concepts and frameworks covered in modules 1-4 are particularly relevant for this assignment. Assignment 2 relates to the specific course learning objectives 1, 2 and 3:

Explain in des data encryption standard, Explain in DES Data Encryption Sta...

Explain in DES Data Encryption Standard : DES stands for Data Encryption Standard and is explained as follows: DES is at present the most widely used key cryptographic systems

What is mac address, MAC Address The address for a machine as it is id...

MAC Address The address for a machine as it is identified at the Media Access Control (MAC) layer in the network structure. MAC address is generally stored in ROM on the n

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