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

Define secure socket layer (ssl), Secure Socket Layer (SSL) accepts a combi...

Secure Socket Layer (SSL) accepts a combination of asymmetric and symmetric (public-key) encryption to accomplish integrity, confidentiality, authentication and non-repudiation for

The cost benefit analysis (cba) formula, The Cost Benefit Analysis (CBA) Fo...

The Cost Benefit Analysis (CBA) Formula CBA determines that whether the control alternative being evaluated is worth cost incurred to control vulnerability or not. CBA easily ca

Benchmarking-information security, Benchmarking An alternative approach to...

Benchmarking An alternative approach to risk management is Benchmarking. It is process of seeking out and studying practices in other organizations which one’s own organization de

Functional areas in network management, Question 1 a) Explain how CSMA...

Question 1 a) Explain how CSMA/CD works. b) Describe the term "exponential back-off". c) Describe the differences between "circuit switching" and "packet switching". d) Th

Types of idss and detection methods, Types of IDSs and Detection Methods ...

Types of IDSs and Detection Methods IDSs operate as network based, host based, or application based systems and focused on protecting network information assets. All the IDSs us

Describe the two possible configurations for 3des, QUESTION (a) Describ...

QUESTION (a) Describe the two possible configurations for 3DES (b) What is the main disadvantage of 3DES? (c) Why are most modern symmetric algorithm block ciphers? (d

How an attacker can effectively de-layer and analyse data, Around the globe...

Around the globe the bank controlled Co-ops (Visa, MasterCard, Discover, and American Express) have rolled out millions of smart cards under the EMV (Europay, MasterCard, VISA) sta

Ring topology, RING TOPOLOGY In this topology of network the devices a...

RING TOPOLOGY In this topology of network the devices are connected to each other in packed loop. In this network first computer passes data packet to the second and then seco

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

Hypothetical reliable data transfer protocol, Hypothetical reliable data tr...

Hypothetical reliable data transfer protocol: A jumping window based Go-back-N  ARQ protocol for file transfer using UDP as the transport protocol: In this protocol, a window o

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