Placeholders for the plaintext characters, Computer Network Security

Assignment Help:

Encode the following plaintext, using the Caesar cipher:

            LORD OF THE RINGS
b) The following ciphertext

            jw njbh lxmn cx kanjt

has been encoded using a generalised Caesar cipher where the following rule computes a character ci in the cipher text from a character pi in the plain text:

ci = E(pi) = pi + d

where d is a positive integer.

Find the number d and the plain text. Hint: use a table of English letter frequencies. This information can be found on the Internet.

c) Now consider the following cipher text:

homlox prv hetorx orxolxpersorx

A more general substitution cipher has been used. Recall that this means that every letter of the alphabet appearing in the plain text is replaced with another unique letter of the alphabet. For example, the letter 'a' could be mapped into 'h', the letter 'b' into 'x' etc. The ciphertext then simply consists of these mapped letters.
Work out the original plain text message, using the following approach:

(i) Write a line of dashes ("_") as placeholders for the plaintext characters corresponding to each letter in the above cipher text. Make sure you also mark the spaces between the different words as they will give you clues as soon as you know some of the letters.

(ii) Using the English letter frequency table, find the letter which the letter "e" is most likely to be replaced with. Use this to replace some of the "_" by the letter "e" (simply copy the last line you wrote and then replace).



Related Discussions:- Placeholders for the plaintext characters

Packet filtering firewall, Packet Filtering Firewall Packet filtering i...

Packet Filtering Firewall Packet filtering is a network security mechanism that works by controlling what data can flow in and out of the network. The basic device that interco

Define checksum, The method used to check errors is checksum . In this m...

The method used to check errors is checksum . In this method data is treated as a sequence of integers and their arithmetic sum is calculated and the carry bits are added to the

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

Who are the individuals who cause these security problems, Who are the indi...

Who are the individuals who cause these security problems? Many unauthorized people who cause network security problems for obtaining information about the other users and causi

Describe how a cellular network works, Problem 1 . Show various features of...

Problem 1 . Show various features of a 1G network Total three features for each feature of 1G Problem 2. Describe how a cellular network works with functional block diagram

Produce a pcap file from a wireshark capture, Question requires you to prod...

Question requires you to produce a pcap file from a Wireshark capture.  In addition, you must include a screen capture of Wireshark and some specific information regarding the fram

Computer Security, I have an assignment of Computer Security to submit. Wil...

I have an assignment of Computer Security to submit. Will you guys help me making my assignment???

Mitigate risks in an information security management system, Question: ...

Question: (a) What are the various options to mitigate risks in an Information Security Management System (ISMS)? For each option specify an instance where it can be used.

Describe des encryption, (a) Describe DES encryption with a block diagram a...

(a) Describe DES encryption with a block diagram and brief steps. (b) How does triple DES improve security. What is the effective key length of triple DES? How can 3DES be compa

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