Now, for example, say, if we create or something like, say, the let's go to your and he I don't
down our cipher letters here and below, we would write down the potential decryption letters and here
we would take forced c h g, h, h you and your we would take the other word that we have created that
is b b y the M or m m y.
Then let's take B or B B Y and and A and and y.
So over here, if you look at it, each has a potential decryption letter of B, M, B or N, similarly,
G has a potential decryption letters, you or A or you have the potential decryption letters.
Why?
So all the others are four letters besides this have no potential decryption letters in this particular
example.
Right.
So a cipher letter mapping shows all the letters of the alphabet and their potential decryption letters.
So as we start to gather encrypted messages, we'll find potential decryption letters for every letter
in the alphabet.
But the only cipher letters that is edgy and you are part of our example.
We don't have potential decryption letters for other cipher letters.
So notice that you has only two potential decryption, only one over here.
That is why, because there are no overlaps between the candidates, which many of which ends with the
letter by itself.
So over here we can use a dictionary value to represent the site letter mapping us follow.
For example, we may use your C4 or say G or in single codes we can use it something like it should
be you then all a for example or for that case.
If we take each, each can be equal to C be then M, B and similarly we can write down C you, which
should be equal to either one.
Now this dictionary has tremendous value that is apart from G h and you you will also have from ABC
to does it and all the others will be basically blank.
You may have C for example, E, which is equal to blank or C let's give comma B, B also has blank,
then C comma C also has blank.
Let's give A commonly also has blank like this for all the others apart from Chenu.
So it shows the potential decryption letters for the G H and you and all the others will have like this
blank as we have represented here.
So because we can reduce the number of potential decryption letters for the cipher letter to just one
letter by cross referencing the cipher little mappings to other encrypted words, we can find what that
cipher letter decrypts to.
Even if we can solve all twenty six cipher letters, we might be able to hack most of this letter mappings
to decrypt most of the ciphertext.
So now that we have covered some part of the basic concepts and some terminologies which we would be
using in this session, let's look at the steps involved in hacking this process.
So let's have an overview of the hacking process.
So the hacking are simple.
Substitution cipher is pretty easy.
Using the four patterns, we can summarize the major steps of hacking process as number one, find the
work pattern for each cipher vote in a ciphertext.
Number two, find the English word candidates that each cipher vote would decrypt to number three,
create a dictionary showing potential decryption letters for each side.
Four letter to act as a cipher letter mapping for each cipher vote.
Number four, combine the five four letter mappings into a single mapping, which we will call, say,
for example, intercepted mappings.
Number five, remove any sort cipher letters from the combined patterns on mappings.
And finally, number six, decrypt the ciphertext with this solved cipher letters.
Now, the more cipher vault in the ciphertext, the more likely it is for mappings to overlap with one
another and the fewer the potential decryption letters for each ciphertext.
This means that in a simple substitution cipher, say one line of text.
So the python hacking advanced level code, this is hacking a simple substitution cipher.
This whole particular line, before dividing into the source code, will have to look at how we can
make the first step of hacking process easier.
So again, in this we would be using the dictionary file used in the earlier session to get the word
pattern for every word in the dictionary file and then saw them in the list.
So coming to our verb pattern module now to calculate the word pattern for every word in the dictionary
of the file, which we have, we would create another file which will check the or make the word patterns
dot python file, and then we will place that particular file, which will have a program to get word
pattern, for example, and it would return the damage of old patterns, which we're passing it as the
parameter.
Now, after creating this file, then only we can go ahead for creating a hacking example for a simple
substitution cipher.
So in the next session, we would see creating of the make vote part file and then we will use that
file along with the dictionary files, which we have from the earlier sessions, and then we will create
our hacking example for simple substitution cipher.
So that's it from this session.