At http://krovetz.net/x52/substitution.txt you will find a text file that has be

Question

At http://krovetz.net/x52/substitution.txt you will find a text file that has been encrypted with a substitution cipher. Only letters have been substituted, not spaces, numbers or punctuation. Upper and lower-case substitutions are the same (ie, if ‘a’ maps to ‘d’, then ‘A’ maps to ‘D’ too). Find the substitution mapping and the original plaintext. Describe the steps you took to solve this problem. If you search for “frequency analysis” online, you will find many tools that will help with this problem.

Explanation / Answer

First observe the cipher text means is it follows any specific format or not.

For ex:If it is a caesar cipher,to employ this method shift each letter of the alphabet a specific number of positions.

Plain: a b c d e f g h i j k l m n o p q r s t u v w x y z
Cipher: D E F G H I J K L M N O P Q R S T U V W X Y Z A B C

But in this problem cipher is a mixed alphabets, as is the case for mixed alphabets,i used online tool.

In that tool add the cipher text it will give plain text.

Cipher Text:

Plain Text:

The ?ole had been wor?ing ver? hard all the ?orning, spring-cleaning his little ho?e. ?irst with broo?s, then with dusters; then on ladders and steps and chairs, with a brush and a pail o? whitewash; till he had dust in his throat and e?es, and splashes o? whitewash all over his blac? ?ur, and an aching bac? and wear? ar?s. Spring was ?oving in the air above and in the earth below and around hi?, penetrating even his dar? and lowl? little house with its spirit o? divine discontent and longing. It was s?all wonder, then, that he suddenl? ?lung down his brush on the ?loor, said 'Bother!' and 'O blow!' and also 'Hang spring-cleaning!' and bolted out o? the house without even waiting to put on his coat. So?ething up above was calling hi? i?periousl?, and he ?ade ?or the steep little tunnel which answered in his case to the gaveled carriage-drive owned b? ani?als whose residences are nearer to the sun and air. So he scraped and scratched and scrabbled and scrooged and then he scrooged again and scrabbled and scratched and scraped, wor?ing busil? with his little paws and ?uttering to hi?sel?, 'Up we go! Up we go!' till at last, pop! his snout ca?e out into the sunlight, and he ?ound hi?sel? rolling in the war? grass o? a great ?eadow. 'This is ?ine!' he said to hi?sel?. 'This is better than whitewashing!' The sunshine struc? hot on his ?ur, so?t bree?es caressed his heated brow, and a?ter the seclusion o? the cellarage he had lived in so long the carol o? happ? birds ?ell on his dulled hearing al?ost li?e a shout. ?u?ping o?? all his ?our legs at once, in the ?o? o? living and the delight o? spring without its cleaning, he pursued his wa? across the ?eadow till he reached the hedge on the ?urther side. E?tract ?ro? 'The Wind in the Willows' b? ?enneth Graha?e Available to read in ?ull at www.gutenberg.org

Then compare which of the letter is substituted, for the easy comparision find the letter frequency(number of occurances in the cipher paragraph)

j : 154
x : 124
w : 112
v : 112
g : 111
f : 107
q : 103
z : 90
k : 77
y : 77
c : 76
i : 45
n : 43
m : 39
d : 34
h : 29
p : 25
u : 25
b : 24
t : 13
l : 12
r : 8
e : 2
o : 1
a : 1
s : 0

In This Problem the substitutions are

a-->?

b-->p

c-->d

d-->c

e-->?

f-->h

g-->i

h-->?

i-->g

j-->e

k-->r

l-->?

m-->u

n-->w

o-->?

p-->b

q-->s

r-->?

s-->not there in cipher

t-->?

u-->?

v-->t

w-->n

x-->a

y-->l

z-->o

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