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

What do you meant by network address translation, Problem: (a) What do ...

Problem: (a) What do you meant by Network Address Translation (NAT)? Why is it used? (b) Given the following information by your ISP about your newly acquired Frame Relay c

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

Symmetric encryption-cryptography, Symmetric Encryption This encryption ...

Symmetric Encryption This encryption method makes use of same “secret key” to encipher and decipher the message and it is termed as private key encryption. This type of encrypti

Describe the functionality of a router, QUESTION: (a) Explain, with the...

QUESTION: (a) Explain, with the aid of a diagram, a Star topology of a network of your choice. (b) Illustrate on the use of a MAN and give an example of one. (c) Describe

Fragment identification, FRAGMENT IDENTIFICATION: IDENT field in every...

FRAGMENT IDENTIFICATION: IDENT field in every fragment matches IDENT field in real datagram. Fragments from different datagrams may arrive out of order and still be saved out.

Define shift operation, SHIFT OPERATION:  This operation replaced all...

SHIFT OPERATION:  This operation replaced all bits to the left one position. For example in the diagram below a 16-bit CRC hardware is given, which needs three Exclusive OR (

Transmission errors in networking, TRANSMISSION ERRORS:  Transmission...

TRANSMISSION ERRORS:  Transmission exceptions may happen due to different causes for example power surges or interference may delete data during transmission. In result of wh

Biology, Ask question #Minimum 100 words are there non parasitic v...

Ask question #Minimum 100 words are there non parasitic viruses

Describe what the term session hijacking means, An overall rise in mobility...

An overall rise in mobility, coupled with the falling cost of Wi-Fi equipment, has led to a proliferation of Wi-Fi hot spots in public areas to provide Internet accessibility. Thus

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