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

Access control matrix, You are provided with 3000 sample keystrokes for 5 u...

You are provided with 3000 sample keystrokes for 5 users mentioned above. You can find this data using the ‘Lab 2 User Data' link in the ‘Lab 2' folder on Blackboard. Please note t

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

Public key cryptosystem based on rsa technology, Problem: (a) What is ...

Problem: (a) What is the minimum length of a password that could be considered to be "strong" in the context of today's computing power? (b) The security of a PIN system,

For providing the security, There are various benefits related with providi...

There are various benefits related with providing the security. They are given below,  (i)  Confidentiality/ Privacy (ii)  Integrity  (iii) Availability (iv)Authenticatio

Explain the encryption model or symmetric cipher model, With explain the en...

With explain the encryption model the help of diagram. Symmetric cipher model uses the secret-key or a single-key for encryption/decryption purposes. It employs a symmetric encr

Network security attacks, (a) Show four Network Security attacks. How do th...

(a) Show four Network Security attacks. How do they compromise security? (b) In what ways do the following devices or services contribute to security: (i) Firewall (ii) In

Vigenere Cipher, What key which if used to encrypt the ciphertext again wou...

What key which if used to encrypt the ciphertext again would give back the plaintext (i.e. key is a weak key)? Define a formula for identifying weak keys for the cipher below (

What is the benefit of adopting a password aging policy, QUESTION (a) H...

QUESTION (a) Hashing and salting is commonly used as password storage techniques for most applications. Describe how hashing and salting enable secure storage of password (b

Virtual packets, VIRTUAL PACKETS These data packets serve same reason ...

VIRTUAL PACKETS These data packets serve same reason in Internet as frames on LAN. Every packet has a header. Routers, which are normally gateways, transfer packets between ph

Listing assets in order of importance-risk management, Listing Assets in Or...

Listing Assets in Order of Importance Weighting should be created for each category based on the answers to questions. The relative importance of each asset is calculated usin

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