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

Asymmetric encryption-cryptography, Asymmetric Encryption Asymmetric encr...

Asymmetric Encryption Asymmetric encryption method makes use of two different but related keys and either key can be used to encrypt or decrypt the message. This method is freque

Address resolution protocol (arp), ADDRESS RESOLUTION PROTOCOL (ARP) T...

ADDRESS RESOLUTION PROTOCOL (ARP) TCP/IP can use any of the three address resolution functions relaying on the addressing procedure used by the underlying hardware. To guarant

Effective legal and ethical frameworks, All references using actual quotes,...

All references using actual quotes, paraphrase, or specific arguments, should employ page numbers. The essay is based on the unit content and should engage with the set readings, a

Basic functions of e-mail system, B a s i c functions of e-mail system ...

B a s i c functions of e-mail system are given as follows: C o mp o sition refers to the procedure of creating messages and the answers. Though any text editor can be

Direct indexing, DIRECT INDEXING It is less usually known method. It i...

DIRECT INDEXING It is less usually known method. It is possible only is cases where protocols address are given from a compact range. In the diagram below an example of direct

Risk control strategies-, Risk Control Strategies Once the ranked vulner...

Risk Control Strategies Once the ranked vulnerability risk worksheet has created, they should choose one of following 4 strategies to control each risk: •Apply safeguards which

Feasibility studies-risk management, Feasibility Studies Before deciding...

Feasibility Studies Before deciding on strategy, all information of economic or non economic consequences of vulnerability of information asset should be explored. A number of w

TCP / IP, Let me know the details of protocol tcp/ip

Let me know the details of protocol tcp/ip

Describe the procedure known as byte stuffing, Question: (a) For the b...

Question: (a) For the bit stream 010011, sketch the waveforms for each of the code indicated. Assume the following: the signal level for the previous bit for NRZI was a 1

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