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Now, let us understand this first manually.

2
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Hence, we have come to this accelerate, not so understanding the finding, repeated sequences, you're

3
00:00:09,060 --> 00:00:17,230
not the first step of your examination is to find every disputed set of at least three letters in ciphertext.

4
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Now, these repeated sequences will be the same length of the plaintext, which is encrypted using the

5
00:00:22,890 --> 00:00:24,390
same subcu of the beginning.

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For example, if you want to encrypt the plain text, like say.

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They'll get.

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Is out all of the Mac now, this basically you want to encrypt, let us just make this size small so

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that it is easy for us to understand.

10
00:00:54,120 --> 00:01:01,410
So and below that, we would write down the key, which will be using for hacking it.

11
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So the key will be using a safe skill.

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No.

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Vince,

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so again, we will continue

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the spin, though, now if you just look at it, if you want to have the text using the key, you will

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get your fill.

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W m and L m b w b why the v x l w m m l z.

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Now, if you look at it over here, this LW M here and the l w m here, this is repeating now this is

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repeating twice.

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The reason is that in the ciphertext LW M is a plain word though, which is interpreted using the same

21
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letter of the FBI because it happens to be repeated a second time.

22
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So the number of letters from the beginning of the first LW M to the beginning of second LW M, which

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we call it as a spacing is thirteen.

24
00:02:18,640 --> 00:02:24,360
Now this suggests that the key used for this ciphertext is 13 letters long.

25
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By just looking at the repeated sequences, you can find out the letter of the key or the length of

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the piece.

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However, in most ciphertext, the key vaunt conveniently align with the repeated sequence of letters,

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or the key might repeat more than once between repeated sequences, meaning that number of letters between

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the repeated letters would be equal to multiply of the key rather than the key itself.

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So to try to address these problems, we will look at a longer example, which we don't know what the

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key is.

32
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So let us take a particular example in this case.

33
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Now, let us write down it over here.

34
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Let's take it c, p, p, q, c, a let's give it a space here.

35
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C, x, u, we k, g, c for moment of giving us this letter simply continued writing this letter to

36
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provide me in a game that you see my B and G, B and C, G and I need to make it all in the same sequence.

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Then let's continue C.

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S or D is that G.

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Why I am then a full stop then let's take we are a G again.

40
00:04:01,890 --> 00:04:08,050
Let's put it in one then C, V or h.t..

41
00:04:09,540 --> 00:04:18,570
We are a u c t is G again a full stop.

42
00:04:20,750 --> 00:04:30,320
Let's align it properly, c, d, d, w, you know, let's take x, i, d.

43
00:04:33,210 --> 00:04:43,320
Then A said you it would be a little much bigger so that we're able for easy for us to understand that,

44
00:04:43,710 --> 00:04:57,450
say we a we we are a z, c, v, v, q, p i, w v all you.

45
00:04:58,770 --> 00:05:02,910
So we have a line this properly.

46
00:05:04,250 --> 00:05:13,250
Now, if you just look at it over here, see this vibe in here, let's highlight this and this is why

47
00:05:13,250 --> 00:05:19,820
we in here are pretty similarly this if you look at it, OK?

48
00:05:19,880 --> 00:05:21,470
Have you made your mistake?

49
00:05:21,980 --> 00:05:22,580
Yes.

50
00:05:22,970 --> 00:05:30,540
After YV and we had missed all this here.

51
00:05:30,560 --> 00:05:41,360
So now this is a do you and similarly, if you look just ahead after a while, you have your also.

52
00:05:41,360 --> 00:05:41,910
Is it.

53
00:05:42,570 --> 00:05:45,190
Now let us give this a different heading.

54
00:05:47,000 --> 00:05:48,460
So the story repeating here.

55
00:05:48,830 --> 00:06:02,870
Similarly, if you just look at another that is severe a similarly we are here and again, we are here.

56
00:06:03,590 --> 00:06:06,920
Even these three words are also repeated.

57
00:06:07,400 --> 00:06:12,190
So this many votes we are having repeating, which we have identified.

58
00:06:12,500 --> 00:06:15,450
So there are several potential villains over here.

59
00:06:15,830 --> 00:06:21,250
Now, the next step of your kazatsky examination will be to calculate all the factors of these count,

60
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to narrow down the potential Keelen.

61
00:06:24,500 --> 00:06:28,540
So not moving to getting the factor of spacing's.

62
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Now, the spacing between the sequences, if you just not on it, you are having three eight eight,

63
00:06:36,080 --> 00:06:39,680
then twenty four, thirty to forty eight.

64
00:06:40,230 --> 00:06:44,530
Now the factor of the spacing are more important than this spacing actually.

65
00:06:45,020 --> 00:06:45,710
So to see.

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00:06:45,710 --> 00:06:46,190
Right.

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We'll just look at the message, for example, see if we take another one.

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See the dog.

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And the.

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At.