Question

A. Explain what is meant by the terms ‘frequency analysis’ and ‘ciphertext’? B. Using Frequency Analysis techniques, work to analyse and decrypt the following ciphertext. "Djk txcmkrr cn nxkfzkgma pgpvarbr bgecvekr mczgdbgi djk cmmzxxkgmk cn kpmj vkddkx bg pg kgmxatdko mbtjkxdkwd. Djbr br lkmpzrk, bg pga ibekg mbtjkxdkwd, mkxdpbg vkddkxr pgo mcylbgpdbcgr cn vkddkxr cmmzx sbdj epxabgi nxkfzkgmbkr. ncx kwpytvk, bg Kgivbrj, sk hgcs djpd djk vkddkxr K, D, P pgo C pxk ycrd mcyycg, sjbvrd vkddkxr rzmj pr S, F pgo W cmmzx vkrr nxkfzkgdva"

Answer 1

Frequency analysis is a cryptanalysis method used to break ciphers by analyzing letter frequencies in ciphertext. Ciphertext is the encoded message produced by the encryption of plaintext. Through frequency analysis, cryptanalysts compare letter frequencies in ciphertext to those expected in the language to unveil the original message.

Step-by-step explanation:

Frequency analysis is a cryptanalysis technique used to break a cipher by studying the frequency of letters or groups of letters in the ciphertext. This technique is based on the fact that, in any given stretch of written language, certain letters and combinations of letters occur with varying frequencies. For example, in English, the letter 'E' is commonly the most frequent letter. By comparing the frequency of letters in the ciphertext to the expected frequency of letters in the language, cryptanalysts can start to piece together the original message, also known as plaintext.

Ciphertext, on the other hand, is the result of encrypting plaintext using a cipher. It is the scrambled message that needs to be deciphered. In the example provided, the ciphertext is an encrypted message that needs to be analyzed and decrypted using frequency analysis techniques. The techniques could involve looking for patterns and frequencies of single letters, as well as pairs or groups of letters (bigrams, trigrams, etc.), to deduce possible substitutions and eventually reveal the plaintext.