I prefer computer typed answer because I could not understan

I prefer computer typed answer because I could not understand bad hand writing.

Also, if you try to answer only part of question for taking your score, I will report you to Chegg. Please do not take my question for free.

The question is related to \'Cryptology and number theory\' course.

Thank you in advance and I apologize for being aggressive because of many free question takers.

Here is a varian of the Kasiski attack: in the ciphertext, look for characters which are the least common in ordinary Enblish, and compute the greatest common divisor of the distances apart of occurrences of identical ones. We\'d then guess that the key length should devide many of theses gcd\'s. Is this reasonable ?

Solution

Cryptography or cryptology (from Greek krypton, \"hidden, secret\"; and graphein, \"writing\", or - -logia, \"study\", respectively is the practice and study of techniques for secure communication within the presence of third parties known as adversaries . More usually, cryptography is about constructing and analyzing protocols that forestall third parties or the public from reading personal messages; varied aspects in info security like information confidentiality, data integrity, authentication, and non-repudiation are central to fashionable cryptography. Modern cryptography exists at the intersection of the disciplines of arithmetic, computer science, and electrical engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce. Cryptography prior to the trendy age was effectively synonymous with coding, the conversion of information from a clear state to apparent nonsense. The originator of associate degree encrypted message shared the decipherment technique required to recover the original info solely with supposed recipients, thereby precluding unwanted persons from doing the same. The cryptography literature often uses Alice for the sender, Bob for the intended recipient, and Eve for the adversary. Since the development of rotor cipher machines in warfare I and also the advent of computers in warfare II, the methods used to perform science became a lot of complicated and its application more widespread. Number theory or, in older usage, arithmetic is a branch of math devoted primarily to the study of the integers. It is sometimes known as \"The Queen of Mathematics\" as a result of its foundational place within the discipline Number theorists study prime numbers as well because the properties of objects created out of integers or defined as generalizations of the integers. Integers can be thought of either in themselves or as solutions to equations Questions in variety theory are typically best understood through the study of analytical objects that encipher properties of the integers, primes or other variety-theoretic objects in some FASHION One may additionally study real numbers in relevance rational numbers, e.g., as approximated by the latter.