1. Show how you can use frequency table to decipher the following ciphertext whi
ID: 3825420 • Letter: 1
Question
1. Show how you can use frequency table to decipher the following ciphertext which is based on the Caesar cipher without knowing the key:
Irkpmwl pmxivexyvi mw xli wxyhc sj pmxivexyvi avmxxir mr xli Irkpmwl perkyeki Xli avmxivw hs rsx rigiwwevmpc lezi xs fi jvsq Irkperh fyx ger fi jvsq epp sziv xli asvph. Mx mrgpyhiw wsqi sj lmwxsvc'w qswx jeqsyw avmxivw Irkpmwl pmxivexyvi hexiw fego qsvi xler jmzi girxyvmiw Mx vitviwirxw avmxivw rsx srpc jvsq hmjjivirx tevxw sj xli asvph erh xmqi tivmshw, fyx mx gszivw izivc qensv kirvi erh wxcpi sj avmxmrk ew aipp
2. Find the plaintext from the cipher. The Caesar cipher is created after shifting the plaintext by key of 4.
Cipher: WIRHLIPT
Explanation / Answer
The main weaknes of Caesars ciphers is that the letters themselves change, their frequency does not changes. So, any one can cryptographer could crack the code using frequency analysis table of the original plaintext text.
Here are the percentages that the letters of the alphabet appear in English:
If we can put them in some order of most frequent letter, it is easy to see that "E" is the most common letter, followed by the letter "T":
In addition to this, English has some number of common letter patterns that we can also be used to help decrypt caecars ciphers:
1. ENGLISH LITERATURE IS THE STUDY OF LITERATURE WRITTEN IN THE ENGLISH LANGUAGE THE WRITERS DO NOT NECESSARILY HAVE TO BE FROM ENGLAND BUT CAN B EFROM ALL OVER THE WORLD IT INCLUDES SOME OF HISTORYS MOST FAMOUSWRITERS ENGLISH LITERATURE DATES BACK MORE THAN FIVE CENTURIES IT REPRESENTS WRITERS NOT ONLY FROM DIFFERENT PARTS OF THE WORLD AND TIME PERIODS BUT IT COVERS EVERY MAJOR GENRE AND STYLE OF WRITING A SWELL
2. Cipher: WIRHLIPT
Plaintext: SENDHELP
A B C D E F G H I J K L M 8.2 1.5 2.8 4.3 12.7 2.2 2.0 6.1 7.0 0.2 0.8 4.0 2.4 N O P Q R S T U V W X Y Z 6.7 7.5 1.9 0.1 6.0 6.3 9.1 2.8 1.0 2.4 0.2 2.0 0.1Related Questions
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