Question

Decrypt the following cipher text obtained from auto key cipher by using exhaustive key search

MALVVMAFBHBUQPTSOXALTGVWWRG

Answer 1

I tried different keys but I got exhausted any help will be appreciated

Answer 2

So the way is Convert the alphabetic string to the numeric string


M A L V V M A F B H B U Q P T S O X A L T G V W W R G
12 1 11 21 21 12 1 5 2 7 2 20 16 15 19 18 14 23 1 11 19 6 21 22 22 17 6



12 1 11 21 21 12 1 5 2 7 2 20 16 15 19 18 14 23 1 11 19 6 21 22 22 17 6

Then we compute




X1 = d9 (12) = (12 - 8 ) mod 26 = 3


X2 = d3(1) = 24

X3 = d24(11) = 13

x4 = d14(21) = 7

x5 = d7(21) = 14

x6 = d14(12) = 24

Answer 3

You can use this calculator if you are lazy
http://britton.disted.camosun.bc.ca/modarith/modular/modcalc.html

Answer 4

The above trial we assume that the key is 9 we start with

Answer 5

Need help in finding the word and the key used ??

Answer 6

If we assume that the key k = 8
then X1 = d8 (12) = (12 - 8 ) mod 26 = 4


X2 = d4(1) = 23

X3 = d23(11) = 14

x4 = d14(21) = 7

x5 = d7(21) = 14

x6 = d14(12) = 24

x7 = d24(1) = 3

EXOHO

Answer 7

Not sure if I did it right or I overlooked some thing

Answer 8

i dont understand this one.. what do u mean by all those numbers?

Answer 9

Ok you first convert the letters above to numbers you know numeric string

Answer 10

nope, never heard of the numeric string.

Answer 11

lool you know it bahrom :P then you compute for the first letter lets say assuming Key = 9 its X1 = d9(M) = d9 (12) = (12-9) mod 26 = 3 you can use the calculator on the link above

Answer 12

then take that result 3 we sub to get the second letter X2 = d3(A) = d3(1) = 24

Answer 13

after finding all the X numbers then we convert them back to the letters that corresponds to those numbers example
X1 = 3 which is C

Answer 14

X2 = 24 which is Y

Answer 15

and so on then if that doesnt work we use a different key K = 8 or K = 10 and run the same operation

Answer 16

im totally lost

Answer 17

come on bahrom

Answer 18

re read it again cant figure out the key

Answer 19

MALVVMAFBHBUQPTSOXALTGVWWRG

Answer 20

gimme like 15 mins.

Answer 21

i was helping someone before we started, let me jstu finish that.

Answer 22

Sure

Answer 23

ok

Answer 24

ok

Answer 25

https://docs.google.com/viewer?a=v&q=cache:-IMzynl-vEQJ:squall.cs.ntou.edu.tw/CryptoIntro/2004fallC1/solutions/chap2sol34893.pdf+&hl=en&gl=us&pid=bl&srcid=ADGEEShGlL5yRQNaX6Q4yIxuatD1nTuTx-dIf67Mt7eritqS3nSTePADiQVVJQxbKYStdtgAUkYO1tsydXoRV2zI0zXSc1dlZ6fIT17b5MUPEpegK9WZF9aSP-ydHI7OBBjDwxSaadFO&sig=AHIEtbQc04oWhg4h6N37g52SwEj0HMPs-A

Answer 26

when all else fails, brute force attack...

Answer 27

It works when K = 19 do you believe that