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Author Topic: Secure (Ish) Cipher  (Read 5442 times)

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Offline JustCause

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Secure (Ish) Cipher
« on: December 01, 2010, 06:41:50 pm »
A simple example program that converts text to ciphertext and back again. Because it uses the rand seed, it's super-secure: unless someone knows it was coded on a calc, they're not getting it decoded.

Supports A-Z and spaces. Key can be any number.

Optimizations welcome.
« Last Edit: December 02, 2010, 10:45:17 am by JustCause »
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SirCmpwn

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Re: Super Secure Cipher
« Reply #1 on: December 01, 2010, 06:43:51 pm »
Removed voluntarily by author.
« Last Edit: December 02, 2010, 12:48:03 am by SirCmpwn »
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Offline AngelFish

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Re: Super Secure Cipher
« Reply #2 on: December 01, 2010, 06:46:39 pm »
Quote from: JustCause on December 01, 2010, 06:41:50 pm
A simple example program that converts text to ciphertext and back again. Because it uses the rand seed, it's super-secure: unless someone knows it was coded on a calc, they're not getting it decoded.

Supports A-Z and spaces. Key can be any number.

Optimizations welcome.

The calc uses L'Ecuyer's algorithm. It's not a very secure pseudo random generator.
« Last Edit: December 02, 2010, 12:56:48 am by Qwerty.55 »
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∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline DJ Omnimaga

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Re: Super Secure Cipher
« Reply #3 on: December 02, 2010, 12:50:37 am »
I do not know about encryption, but could you show examples of what would a certain word show up as when encrypted?

That said, although I think SirCmpwn's comment was uncalled for, it is pretty hard to have a secure encryption on a calc, even in BASIC. In my RPG The Reign of Legends 3, save files are compressed and encrypted using my own compression methods, but anyone who look at the code and understands BASIC could easily figure it out.
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Offline AngelFish

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Re: Super Secure Cipher
« Reply #4 on: December 02, 2010, 12:56:58 am »
 Looking at the code, that's actually a pretty good algorithm. What I would recommend is that you manipulate the strings during computation to take advantage of the avalanche effect in another way. It would also make it a lot more difficult to understand how the algorithm works. I have some example code I can post if you'd like.
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∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline DJ Omnimaga

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Re: Super Secure Cipher
« Reply #5 on: December 02, 2010, 03:20:03 am »
That would be cool :D
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Offline AngelFish

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Re: Super Secure Cipher
« Reply #6 on: December 02, 2010, 03:24:02 am »
Now where did Battlefield go...

Ah, here it is:

Code: [Select]
:" →Str2
:" →Str1
:Repeat length(Str2)=7
:Repeat Ans>40 and Ans<94 or Ans=102
:getKey→K
:End
:If Ans≠44 and Ans≠45 and Ans<94:Then
:Ans-20-5int(.1Ans
:Str2+sub("ABC  DEFGHIJKLMNOPQRSTUVWXYZ",Ans,1→Str2
:Text(26,2,sub(Str2,2,length(Str2)-1
:End
:If K=45 and length(Str2)>1:Then
:sub(Str2,1,length(Str2)-1→Str2
:Text(26,1,"                     "
:Text(26,1,Str2
:End
:If K=102:Then
:Str2+" →Str2
:Text(26,1,Str2
:End
:End


:sub(Str2,2,length(Str2)-1→Str2
:Text(26,2,Str2
:"TEYGJKMNOQRAUBCIVWDLEFHSZ "→Str3
:For(A,1,6
:Str1+sub(Str2,7-A,1)→Str1
:End
:sub(Str1,2,6→Str2
:For(A,1,6
:inString(Str3,sub(Str2,A,1→B
:length(Str3)→D
:(C-B)/(B+C)+B*C→C
:End

This is the reasonably fast algorithm I used in Battlefield. It's not the best one I had, but it's good enough. See if you can understand how it works.

Also, if following the program flow gives you a headache, you should have seen the previous version  :devil:

On a side note, this is about as close to SMC as you can get in BASIC without a ton of Goto statements.
« Last Edit: December 02, 2010, 03:37:59 am by Qwerty.55 »
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∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline DJ Omnimaga

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Re: Super Secure Cipher
« Reply #7 on: December 02, 2010, 03:35:42 am »
I'll probably have to concentrate a bit to understand. I have troubles reading other people code. ;D
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Offline AngelFish

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Re: Super Secure Cipher
« Reply #8 on: December 02, 2010, 03:37:40 am »
Following the String manipulation is the difficult part. Try to concentrate on the second part (after
":sub(Str2,2,length(Str2)-1→Str2")
« Last Edit: December 02, 2010, 03:38:28 am by Qwerty.55 »
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∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline DJ Omnimaga

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Re: Super Secure Cipher
« Reply #9 on: December 02, 2010, 03:42:34 am »
I'll probably also have to run parts of the program a few times to analyze it, since I'm more visual. :P
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Offline AngelFish

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Re: Super Secure Cipher
« Reply #10 on: December 02, 2010, 03:45:42 am »
Here's the routine in a BASIC program
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∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline DJ Omnimaga

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Re: Super Secure Cipher
« Reply #11 on: December 02, 2010, 03:51:42 am »
Oh thanks that might save me some time lol, although since your code was in SourceCoder format (noticing the STO symbol used) I could have copied it on my calc. :D

Being visual is most likely what hindered me when I tried to learn ASM from ASM in 28 days D:
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Offline AngelFish

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Re: Super Secure Cipher
« Reply #12 on: December 02, 2010, 03:54:04 am »
I already had the routine open in sourcecoder and that way everyone can try the code for themselves, rather than having to copy it into their calc.
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∂²Ψ    -(2m(V(x)-E)Ψ
---  = -------------
∂x²        ℏ²Ψ

Offline JustCause

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Re: Secure (Ish) Cipher
« Reply #13 on: December 02, 2010, 10:46:21 am »
Topic title changed. To be fair, when I said "secure" I meant "your crypto nerd friends will go at it for about a week," rather than "1024-bit RSA suitable for issues of national security."

Though I did make 16-bit RSA once. :)
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Offline DJ Omnimaga

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Re: Secure (Ish) Cipher
« Reply #14 on: December 02, 2010, 07:20:53 pm »
How long does a 16 bit key takes to get factored on-calc? What about a recent computer?
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