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

Determine the round trip time, a) determine the RTT (round trip time) betwe...

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. Assume a one-way propagati

Protocols for secure communications-cryptography, Protocols for Secure Comm...

Protocols for Secure Communications Securing Internet Communication by using S-HTTP and SSL Secure Socket Layer (SSL) protocol is a protocol that uses public key encryption t

Cracking the Vigenere Cipher, The following message was enciphered with a V...

The following message was enciphered with a Vigenère cipher. aikiaawgfspxeppvjabjnivulfznzvkrlidamsmyamlvskniyffdpbwtnxsvvbtnamvltsefoeycztkomylmerkwrs deusjgecmzkwvnreeyp

What are the intermediate systems and how they work, Question: a) Expla...

Question: a) Explain what the following intermediate systems are and how they work? i. Repeater ii. Bridge b) A service is formally specified by a set of primitives (op

Discuss the influence the commercial operations, Question: A regional p...

Question: A regional police force has the following corporate objectives: ? to reduce crime and disorder; ? to promote community safety; ? to contribute to delivering just

CS, Discuss how developers should apply the following countermeasures to im...

Discuss how developers should apply the following countermeasures to improve the security of their code:

Risk assessment, RISK ASSESSMENT Risk assessment is a step in a risk man...

RISK ASSESSMENT Risk assessment is a step in a risk management technique. Risk assessment is the determination of quantitative or qualitative value of risk related to a concrete

What are the ethical issues and implications, An injunction to 'think ethic...

An injunction to 'think ethically' about a situation is not helpful. Perhaps if one has a background in moral philosophy this would work, but usually both students and IT professio

Typical network management system, Problem 1: List measurable entities ...

Problem 1: List measurable entities on which the quality of service in a data communication network depends Problem 2: Show the features of a typical Network Management

Datagram reassembly, DATAGRAM REASSEMBLY Recreation of original datagr...

DATAGRAM REASSEMBLY Recreation of original datagram is known as reassembly. Ultimate receiver acts reassembly as given below.Fragments can reach out of order. Header bit check

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