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

Datagram reassembly, DATAGRAM REASSEMBLY Recreation of original datagr...

DATAGRAM REASSEMBLY Recreation of original datagram is known as reassembly. Ultimate receiver acts reassembly as given below.Fragments can reach out of order. Header bit check

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

Ip datagram, IP DATAGRAM Various options can be included to IP header,...

IP DATAGRAM Various options can be included to IP header, e.g., source route, record route and timestamp. Header with no function has H. LEN field value 5; data starts immedia

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

Briefly list functions of a public key infrastructure, Question: (a) Wh...

Question: (a) What is the major problem with public key encryption when compared to symmetric key encryption? (b) Consider the following protocol for communication between t

Ethernet network, QUESTION : a) A datagram of 3000 bytes has to travel...

QUESTION : a) A datagram of 3000 bytes has to travel over a network with a MTU size of 1000 bytes. Describe how fragmentation can be used to solve this problem. You should pr

Malicious node detection mechanisms, Many applications are vulnerable to in...

Many applications are vulnerable to intrusion attacks and can provide misleading reports about misbehaving nodes. Some of the mechanisms under such a category include the Bayesian

Nstissc security model, NSTISSC SECURITY MODEL The NSTISSC Security Model ...

NSTISSC SECURITY MODEL The NSTISSC Security Model provides a detailed perspective on security. While the NSTISSC model covers the 3 dimensions of information security, it removes

Plaintext, how to encryt the data in plaintext cipher

how to encryt the data in plaintext cipher

Identify possible controls-information security, Identify Possible Controls...

Identify Possible Controls For each threat and linked vulnerabilities which have residual risk, create primary list of control ideas. Residual risk is the risk which remains to

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