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

Configuration for 3des, (a) Explain the two possible configuration for 3DE...

(a) Explain the two possible configuration for 3DES. (b) What is the main disadvantage of 3DES? (c) Why are most modern symmetric algorithm block ciphers? (d) Describe

Token ring, TOKEN RING Many LAN methods that are ring topology need to...

TOKEN RING Many LAN methods that are ring topology need token passing for synchronized access to the ring. The ring itself is acts as a single shared communication phase. Both

X.509, Consider the details of the X.509 certificate shown below. a. Identi...

Consider the details of the X.509 certificate shown below. a. Identify the key elements in this certificate, including the owner''s name and public key, its validity dates, the nam

Arp responses, ARP RESPONSES Let's search out how does a computer know...

ARP RESPONSES Let's search out how does a computer know whether an incoming frame have an ARP message. The type field in the frame header defines that the frame contain an ARP

Security services, (a) Mention the five main security services. (b) What...

(a) Mention the five main security services. (b) What is a passive attack? Give an example of passive attack? (c) What four types of active attacks and mention their respecti

Define full-duplex., A  full-duplex (FDX) , accepts communication in both...

A  full-duplex (FDX) , accepts communication in both ways, and, unlike half-duplex, accept this to occur simultaneously. Land-line telephone networks are full-duplex, since they

Encryption, How safe is the encryption of virtual private networks?

How safe is the encryption of virtual private networks?

Unguided media, Unguided Media This is the wireless media that transfe...

Unguided Media This is the wireless media that transfer electromagnetic waves without using a physical media. Waves are broadcast through the air. This is performing through r

Define network, A Network is described as a system for connecting compu...

A Network is described as a system for connecting computers using a single transmission technology. The computers can interact with each other in a network. They can receive an

Use the chinese remainder theorem to evaluate x, Use the Chinese remainder ...

Use the Chinese remainder theorem to evaluate x from the following simultaneous congruences: x ≡ 1 (mod 2); x ≡ 2 (mod 3); x ≡ 3 (mod 5). Calculate gcd(14526, 2568). (

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