ciphertext, 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:- ciphertext

Explain the term virtual private network, Question: (a) Besides privac...

Question: (a) Besides privacy, what other security functions does Pretty Good Privacy (PGP) provides? (b) What is the Post Office Protocol (POP) used for? Why is it impo

Improving domain blacklisting - spam mail, Improving domain blacklisting: ...

Improving domain blacklisting: Current domain blacklisting techniques are not very effective as spammers keep replacing blacklisted domains with newly registered domains. Also

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

Develop firewall rules, Question requires you to develop firewall rules bas...

Question requires you to develop firewall rules based on a fictitious organisation. Scenario: You work for a security-conscious company, xC-Cure, who develop encryption tec

Udp communication semantics, UDP COMMUNICATION SEMANTICS:  UDP needs I...

UDP COMMUNICATION SEMANTICS:  UDP needs IP for all delivery, that is, similar best effort delivery as IP. To use UDP, an application have to either be immune to the causes or

A small isp requests your help, QUESTION A small ISP requests your help...

QUESTION A small ISP requests your help. The technicians report that they have had no downstream access to the Internet. They believe the problem lies with their access provide

Securities Issues in a company, 'Near Field Communication' (NFC) technologi...

'Near Field Communication' (NFC) technologies are expected to become commonplace in the near future. Some relevant features are these: A suitable device (such as a mobile pho

Transport protocols, TRANSPORT PROTOCOLS: Give application-to-appl...

TRANSPORT PROTOCOLS: Give application-to-application communication. Require extended addressing mechanisms to check applications. Are known end-to-end communicatio

What are the main objectives of a risk analysis, QUESTION 1 Risk ana...

QUESTION 1 Risk analysis helps companies prioritize their risks and shows management the amount of money that should be applied to protecting against those risks in a sensib

Discuss a communication channel, Question An organization is planning t...

Question An organization is planning to connect its networks to the Internet. The network is located within a four story building. A web server supporting online sales is also

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