we want to crack this message number 459

from the public message board at crypto

club org we know it was encrypted using

an affine cipher but we don't know the

key there are three ways to approach

cracking an affine cipher first look at

frequencies and word patterns to

determine a few letters in Words with

luck we can crack the entire message

this way but we only need to find the

encryption of two different letters to

use algebra to find the multiplicative

an additive keys then decrypt the rest

of the message using these keys

a third way is to look for patterns in

the cipher table we know how to

construct an affine cipher table using

the multiplicative and additive keys so

let's see how this method works here's

our message on the crack substitution

tool we'll be looking for number

patterns so let's set the cipher table

to show the numbers as well as the

letters to get started cracking first

look at the frequencies we notice that Z

is by far the most common letter in the

message so it makes sense to set Z to e

now look at that first word with

apostrophe I'm betting that that's the

word I've and I'm just going to enter it

I glanced over the message to make sure

that makes sense all the way through and

I know some other things I have another

1 letter word down here and since I've

already used I I'm betting this one is a

so I enter that finally I'm going to

look down at this word V I II and finish

it off with a W now let's switch our

attention to the cipher table I know

that to proceed left to right in the

cipher numbers I must add the

multiplicative key each time but here we

have 6 followed by 11 the multiplicative

key must be 5

and now I can proceed to fill in the

rest of the table by adding five as I go

across 11 plus 5 is 16 16 plus 5 is 21

21 plus 5 is 26 and I know I have to

reduce that to 0 then I skipped to the

beginning of the table five plus five is

10 10 plus 5 is 15 and 15 plus 5 is 20

now I get to 30 which reduces to 4 I'm

going to fill in the rest of the table

and you can yourself confirm that it's

right

you

now I can rid the message from the

message box I've always felt that a

person's intelligence is directly

reflected by the number of conflicting

points of view he can entertain

simultaneously on the same topic and

this quote comes to us from Abigail

Adams and an apt message for us today

because while these methods are not

necessarily conflicting points of view

it does help if we can entertain them

simultaneously to help crack an affine

cipher