Cryptography Method

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Summary:

Any help?

Cryptography Method

L1k3awh15p3r 14 Jan 2014 00:04

Hi guys,

I've always been interested in cryptography, the act of coding something into either meaningless or much less revealing phrases or characters to hide the real message. I've decided I'm going to make a few cryptography programs for my calculator but they're proving much more difficult than I expected.

First I chose to do something simple: Input a string and return a string. You input letters or a word and it returns the alphabetical number that corresponds to the letter: A is 1, E is 5, Z is 26, etc. I figured this would be basic enough for a start.

My concept is that you input the string. The code checks the length of the string and starts a For loop: With 1 as the start and the length of the string that was inputted as the end, it stores the value in for A. Then, it runs through the original string with sub( commands to pick each letter out, storing each one as String 0.

This is where I'm stuck. Let's say I have the string "EXAMPLE" as the original string. I can pick the word apart so I have "E" as Str0, then "X" as Str0, and so on to the last "E." But I don't know how to correspond that to the number. Here's my code, maybe that will help!

Program:CRYPT
:ClrHome
:"0102030405060708091011121314151617181920212223242526→Str1
:Input "Str: ",Str2
:length(Str2)→L
:For(A,1,L
:sub(Str2,A,1→Str0
:***Stuff that I'm missing***
:End

So that's as far as I got. I know I have to put something were I have the comment. I don't know what to do… I remember I had it a few days ago but I foolishly deleted it and now I don't remember how I did it.

Any help is appreciated! Thanks!

-Likeawhisper

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The man shuddered as the shadow drew a glistening sword from his back. Creeping closer and closer with his pale eyes burning into the man, the shadow slowly raised his blade and before he could thrust it down, the man heard the shadow hiss something.
"The Shadow Clan's presence must be like a whisper. Always felt, but never seen…"

Re: Cryptography Method

Timothy Foster 14 Jan 2014 00:28

This page may have stuff relevant to the particular encoding you are using here.

Otherwise, you will want to read about inString( for your particular code.

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Timothy Foster - @tfAuroratide
Auroratide.com - Go here if you're nerdy like me

Re: Cryptography Method

L1k3awh15p3r 14 Jan 2014 20:21

WOW! inString was just the command I needed. Thanks a lot Timothy, this really helps. In a few minutes as soon as I get my revised code I'll put my new code in and you guys can let me know if I'm doing a good job.

Thanks again

---

The man shuddered as the shadow drew a glistening sword from his back. Creeping closer and closer with his pale eyes burning into the man, the shadow slowly raised his blade and before he could thrust it down, the man heard the shadow hiss something.
"The Shadow Clan's presence must be like a whisper. Always felt, but never seen…"

Re: Cryptography Method

L1k3awh15p3r 14 Jan 2014 21:35

I have my new code!!!

PROGRAM:CRYPT
:ClrHome
:ClrDraw
:0→C
:"ABCDEFGHIJKLMNOPQRSTUVWXYZ→Str9
:Input "Text: ",Str1
:length(Str1→L
:For(A,1,L
:sub(Str1,A,1→Str2
:inString(Str9,Str2→B
:Text(C,11A,B
:End

Okay, now for some explanations.

What happens is similar to my first code: It takes in the text you want to translate and stores its character length as L. Using L, we make a custom For( loop that runs from 1 to L. Inside the loop we cut out a single letter from the inputted text and, using inString, search for the letter in the large list of letters, which is Str8. Finding how far away from the letter A the cut out letter is determines its placement in the alphabet. Then it outputs the letter on the graph screen so we have a bit more space.

If you are very attentive or have put the program into your calculator you will notice that the spacing between the numbers is very large. There also is a large space before the first number.

There are some issues I want to fix. I want to make it so that the code tests the length of B (most likely a simple "if B is larger than 9") and then, based on the result, places the number closer or farther away from the previous number. This will hopefully delete the large spaces that are between the numbers.

I also want it to word wrap. If I am going to translate a long sentence, I would have to use fragment by fragment or I will get a boundary error.

To fix these sentence spaces and the word wrapping I have C stored as 0, which is the row that the letters are being displayed on. Please use this C if you are going to post some explanation code, thanks.

Any help? I've experimented but I can't find the solution.

-Likeawhisper

---

The man shuddered as the shadow drew a glistening sword from his back. Creeping closer and closer with his pale eyes burning into the man, the shadow slowly raised his blade and before he could thrust it down, the man heard the shadow hiss something.
"The Shadow Clan's presence must be like a whisper. Always felt, but never seen…"

Last edited on 14 Jan 2014 21:36 by L1k3awh15p3r Show more

Re: Cryptography Method

Timothy Foster 15 Jan 2014 00:11

Imagine the field like a grid in which one space is occupied by exactly one element. Pretend for now that our grid is exactly 3x3 in size:

0	1	2
3	4	5
6	7	8

Here, I have also populated each of the cells with an index number. So the top left cell is Cell 0, and the bottom right is Cell 8. Therefore, if I have a list (or a string) of 9 elements, I can use a For loop through each element and display them in the appropriate slots on my table.

The problem, however, is that the computer does not know where Cell 6 is, or Cell 4, or any Cell. We need to tell it in terms of something it does know: coordinates. Therefore, using our single number, called I, we need to express each cell in terms of some coordinate.

Concentrate on the y-coordinate first, since that is the easiest one. We see that the first row is represented by y=0, the second by y=1, and the third by y=2. The y-coordinate increases by one at every multiple of 3. In other words, 3y = I. You can see that when I is equal to 3, then y = 1 (hence 3y = 3). Therefore, by algebra, the y coordinate is expressed: y = int(I/3). You need the int() since y must be an integer.

You need similar logic to find the x-coordinate. We see that when I=0, x=0; when I=1, x=1. However, when I=3, x=0. Now, the x coordinate resets at every multiple of 3. What if we try dividing again? We get:

• I = 0; I/3 = 0 remainder 0
• I = 1; I/3 = 0 remainder 1
• I = 2; I/3 = 0 remainder 2
• I = 3; I/3 = 1 remainder 0
• …

From this, you can see that the remainders follow the pattern we want! Therefore, the x coordinate is represented by x = remainder(I, 3) = 3fPart(I/3).

Therefore, in terms of I, we have the position of each element given by (3fPart(I/3), int(I/3)).

You'll need to figure out how to apply this to your particular case, but this logic applies with many fixed grid systems.

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Timothy Foster - @tfAuroratide
Auroratide.com - Go here if you're nerdy like me

Last edited on 15 Jan 2014 02:15 by Timothy Foster Show more

Re: Cryptography Method

L1k3awh15p3r 15 Jan 2014 01:59

That actually makes a lot of sense. I'll play around with the program and if I get something that works I'll post it here again.

Thanks

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The man shuddered as the shadow drew a glistening sword from his back. Creeping closer and closer with his pale eyes burning into the man, the shadow slowly raised his blade and before he could thrust it down, the man heard the shadow hiss something.
"The Shadow Clan's presence must be like a whisper. Always felt, but never seen…"