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

Corresponding access control matrix, Consider a computer system with three ...

Consider a computer system with three users: Alice, Bob and Cindy. Alice owns the file alicerc, and Bob and Cindy can read it. Cindy can read and write the file bobrc, which Bob ow

Digital signatures, Digital Signatures Digital Signatures are encrypted ...

Digital Signatures Digital Signatures are encrypted messages which can be proven mathematically to be authentic. These are created in response to rising requirement to verify in

TCP/IP v OSI, What are the main differences between TCP/IP vs OSI?

What are the main differences between TCP/IP vs OSI?

Netfilter firewall, Netfilter Firewall Netfilter is the popular name f...

Netfilter Firewall Netfilter is the popular name for the packet filtering system installed by default in the Linux kernel. The filtering system can be used as a very effective

Ip address, How to find an ip address?

How to find an ip address?

Ipv6 next header, IPV6 NEXT HEADER It is given in the figure below:

IPV6 NEXT HEADER It is given in the figure below:

Caralouer case study: analysis and design techniques, CarALouer provides re...

CarALouer provides rental of cars to its customer on a regional basis i.e. a car is attached to a regional home-base which also houses a regional office of the company. Each regi

Data classification and management, Data Classification and Management C...

Data Classification and Management Corporate and military organizations use a several of classification schemes. Information owners are responsible for classifying information a

define broadcast, In broadcast topology there are further two types 1) ...

In broadcast topology there are further two types 1) SATELLITE\RADIO 2) RING TOPOLOGY In a radio or satellite topology every computers are connected to each other via radio o

Operation of the signature based intrusion detection system, Question : ...

Question : (a) State whether the following statement is FALSE or TRUE: It is always better to have various access points to the Internet so that if a hacker takes one down you

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