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copyable Ciphertext: lrvmnir bpr sumvbwvr jx bpr lmiwv yjeryrkbi jx qmbm wi bpr

ID: 3840509 • Letter: C

Question

copyable Ciphertext:

lrvmnir bpr sumvbwvr jx bpr lmiwv yjeryrkbi jx qmbm wi bpr xjvni mkd ymibrut jx irhx wi bpr riirkvr jx ymbinlmtmipw utn qmumbr dj w ipmhh but bj rhnvwdmbr bpr yjeryrkbi jx bpr qmbm mvvjudwko bj yt wkbrusurbmbwjk lmird jk xjubt trmui jx ibndt
wb wi kjb mk rmit bmiq bj rashmwk rmvp yjeryrkb mkd wbi iwokwxwvmkvr mkd ijyr ynib urymwk nkrashmwkrd bj ower m vjyshrbr rashmkmbwjk jkr cjnhd pmer bj lr fnmhwxwrd mkd wkiswurd bj invp mk rabrkb bpmb pr vjnhd urmvp bpr ibmbr jx rkhwopbrkrd ywkd vmsmlhr jx urvjokwgwko ijnkdhrii ijnkd mkd ipmsrhrii ipmsr w dj kjb drry ytirhx bpr xwkmh mnbpjuwbt lnb yt rasruwrkvr cwbp qmbm pmi hrxb kj djnlb bpmb bpr xjhhjcwko wi bpr sujsru msshwvmbwjk mkd wkbrusurbmbwjk w jxxru yt bprjuwri wk bpr pjsr bpmb bpr riirkvr jx jqwkmcmk qmumbr cwhh urymwk wkbmvb

Computer Science & Information Technology CIS4362 Homework 1 Professor Houssain Kettani Question 1: The ciphertext below was encrypted using a substitution cipher. Decrypt the ciphertext without knowledge of the key. lrvmnir bpr sunn vbwvr jx bpr lmi wv yje ryrkbi jx m wi bpr xjvni mkd ynnibrut jx irhx wi bpr riirkvr jx ymbinlmtmipw utn q nnumbr dj w ipmhh but bj rhnvwdmibr bpr yjeryrkbi jx bpr qmbm innvvjudm ko bj yt w kbrusurbrmbwjk lmird jk xjubt trmui jx ibndt wb wi kjb mk rmit bmiq bj rashmwk rmvp yjeryrkb mk d wibi iw okwxwvmk vr mk d ijyr ynib urymwik nkrashmwkrd bj ower m vjyshrbr rashtrmkmbwjk jkr cjnhd prmer bj lr fnmhwxwrd mkd wki swurd bj invp mk rabrkb bpmb pr vjnhd urmvp bpr ibmbr jx rkhwopbrkrd ywkd vmsmlhr j x turvjokwgwko ijnkdhrii ijnkd mkd ipms rhri i ipmsr w dj kjb drry yti, rhx bpr xw kmh mnbpjuwbt lnb yt rasruwrkvr cwbp qmbrm prni hrxb kj djnlb bpmb bpr xjhhjcwko wi bpr suj sru msshwwmbwjk mk d wkbrusurlbmbowjk w XXru. yt bprjuwr i wk bpr pj sr bpmb bpr riirkvr jx jqwkmcmk qmumbr cwhh urym wsk kbmvb a. Compute the relative frequency of all letters A in the ciphertext. You may want to use a tool such as the open-source program CrypTool [50] for this task. However, a paper and pencil approach is also still doable. b. Decrypt the ciphertext with the help of the relative letter frequency of the English language (see Table 1.1 in Sect. 1.2.2). Note that the text is relatively short and that the letter frequencies in it might not perfectly align with that of general English language from the table. c. Who wrote the text?

Explanation / Answer

TOTAL AND RELATIVE LETTER FREQUENCY IN CYPHERTEXT.
letter count    freq
a    5    0.00773994
b    68    0.105263
c    5    0.00773994
d    23    0.0356037
e    5    0.00773994
f    1    0.00154799
g    1    0.00154799
h    23    0.0356037
i    41    0.0634675
j    48    0.0743034
k    49    0.0758514
l    8    0.0123839
m    62    0.0959752
n    17    0.0263158
o    7    0.0108359
p    30    0.0464396
q    7    0.0108359
r    84    0.130031
s    17    0.0263158
t    13    0.0201238
u    24    0.0371517
v    22    0.0340557
w    47    0.0727554
x    20    0.0309598
y    19    0.0294118

r : 84
b : 68
m : 62
k : 49
j : 48
w : 47
i : 41
p : 30
u : 24
h : 23
d : 23
v : 22
x : 20
y : 19
s : 17
n : 17
t : 13
l : 8
o : 7
q : 7
c : 5
a : 5
e : 5
g : 1
f : 1
z : 0

2 letter sequences


bp => 19
mb => 15
wk => 15
pr => 14
mk => 11
br => 10
jx => 10
bm => 10
pm => 9
rk => 9
kd => 9
ry => 8
kb => 8
mi => 7
ib => 7
kr => 7
rb => 7
jk => 7
ur => 7
rd => 6
rm => 6
bj => 6
ri => 6
ru => 6
mv => 6
rj => 6
ir => 6
ij => 6
bw => 6
ii => 5
ra => 5
qm => 5
wj => 5
vr => 5
sh => 5
jn => 5
sr => 5
wi => 5
er => 5
mw => 5
hr => 5
um => 4
su => 4
wb => 4
bb => 4
as => 4
hm => 4
km => 4
kw => 4
kj => 4
ms => 4
vj => 4
ym => 4
vm => 4
rh => 4
yr => 4
bi => 4
rx => 4
xj => 4
xw => 4
rr => 4
wv => 4
ju => 4
dw => 4
dj => 4
ip => 4
xb => 4
kv => 4
yt => 4

3 letter sequences


bpr => 14
mkd => 6
rjx => 5
wjk => 4
ras => 4
mwk => 4
bwj => 4
bbp => 4
mbr => 4
rkb => 4
rii => 4
kvr => 4
wkb => 4
mbw => 4

4 letter sequences


bwjk => 4
mbwj => 4

5 letter sequences


mbwjk => 4

6 letter sequences

r : 84
b : 68
m : 62
k : 49
j : 48
w : 47
i : 41
p : 30
u : 24
h : 23
d : 23
v : 22
x : 20
y : 19
s : 17
n : 17
t : 13
l : 8
o : 7
q : 7
c : 5
a : 5
e : 5
g : 1
f : 1
z : 0

2 letter sequences


bp => 19
mb => 15
wk => 15
pr => 14
mk => 11
br => 10
jx => 10
bm => 10
pm => 9
rk => 9
kd => 9
ry => 8
kb => 8
mi => 7
ib => 7
kr => 7
rb => 7
jk => 7
ur => 7
rd => 6
rm => 6
bj => 6
ri => 6
ru => 6
mv => 6
rj => 6
ir => 6
ij => 6
bw => 6
ii => 5
ra => 5
qm => 5
wj => 5
vr => 5
sh => 5
jn => 5
sr => 5
wi => 5
er => 5
mw => 5
hr => 5
um => 4
su => 4
wb => 4
bb => 4
as => 4
hm => 4
km => 4
kw => 4
kj => 4
ms => 4
vj => 4
ym => 4
vm => 4
rh => 4
yr => 4
bi => 4
rx => 4
xj => 4
xw => 4
rr => 4
wv => 4
ju => 4
dw => 4
dj => 4
ip => 4
xb => 4
kv => 4
yt => 4

3 letter sequences


bpr => 14
mkd => 6
rjx => 5
wjk => 4
ras => 4
mwk => 4
bwj => 4
bbp => 4
mbr => 4
rkb => 4
rii => 4
kvr => 4
wkb => 4
mbw => 4

4 letter sequences


bwjk => 4
mbwj => 4

5 letter sequences


mbwjk => 4

6 letter sequences

Decrypted message

1 because the practice of the basic movements of kata is
2 the focus and mastery of self is the essence of
3 matsubayashi ryu karate do i shall try to elucidate the
4 movements of the kata according to my interpretation
5 based on forty years of study
6
7 it is not an easy task to explain each movement and its
8 significance and some must remain unexplained to give a
9 complete explanation one would have to be qualified and
10 inspired to such an extent that he could reach the state
11 of enlightened mind capable of recognizing soundless
12 sound and shapeless shape i do not deem myself the final
13 authority but my experience with kata has left no doubt
14 that the following is the proper application and
15 interpretation i offer my theories in the hope that the
16 essence of okinawan karate will remain intact

The text appears to have been written by Shoshin Nagamine in The Essence of Okinawan Karate-Do