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

Calculate the false rejection, Divide the user data into 6 equal sets. Use ...

Divide the user data into 6 equal sets. Use the first set for the enrollment phase of your system, and the rest for the verification phase. Use the following formula to calculate t

Application layer protocol, Problem a) Give the destination IP address, up...

Problem a) Give the destination IP address, upper layer protocol, TTL in decimal and header checksum in hexadecimal; the source port number and the destination port number in deci

Media, what is guided media or unguided media

what is guided media or unguided media

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

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

Ask question #Minimum 100 words are there non parasitic viruses

Potential risks to information systems, Information System Security 1. ...

Information System Security 1. Write about: a. Potential Risks to Information Systems b. Factors to be addressed for making information systems more secure 2. Write about t

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

Error reporting mechanism (icmp), ERROR REPORTING MECHANISM (ICMP) INT...

ERROR REPORTING MECHANISM (ICMP) INTRODUCTION:  IP gives best-effort delivery. Delivery causes can be ignored; datagrams may be 'dropped on the ground'. Internet Control Me

Cyclic redundancy check (crc), CYCLIC REDUNDANCY CHECK (CRC) To activa...

CYCLIC REDUNDANCY CHECK (CRC) To activate a network system to check move error without increasing the amount of information in every packet another most successful method is m

Mobile wireless networks , Is standard TCP effective in mobile wireless net...

Is standard TCP effective in mobile wireless networks that operate with the IEEE 802.11 wireless local area network protocol?Discuss the issue

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