A challenge!
 

The attatched file is a string which I have encrypted using a little encryption script I put together whilst bored. I'd like to see how difficult the algorithm is to crack, so I've taken a text string 183 characters long and run it through the program.

The file looks fairly daunting, and that's probably something to do with the fact that it is. I don't think this will be an easy task, but what the hey! That's the reason I posted this. To see how good the script is.

About the only thing I can tell you is that the original text string is padded based on a user-determined checksum which repeats throughout the string.

Good luck breaking the code, and if enough people show some kind of vague interest in this, I just might post the code that handles encryption and decryption so you can use it yourself.

Encrypted Code:

NPC Code:

---

ENC-TxhlAGJipJsjuDl_ YIzPnB_gzikHpZ]QgsanR sWNtVaP Zqn_s|hiuf`RamnXgTPQ_Z^pAf^]Khqll_wevfvpy ItqMSXeMkxD|UsJtiEFHmYXE] kAI^]\Ws`lbt{UfvurjiYHq[nIQgXSufE xxmjIaREedODGV]jAedVEskLsDli_gR[wZn]xetockrdlZDk_OhDo iqbWiyFtPneoeGdKN _sixZ{hKIoHLe\CwCI\rfue_E {__zxZHhaGfo`PTfHwL QkSOttJhy_vEgixjvKF]e^FsemvgIQd cOFek{LxSnOc[\NjriXyVxk^OpkHxqIdXWftSzuaQ^RivBHoKQKM`nq zf_Es`WyoMgyQsQKoxL[p\\tTBZ[g\DeIVtmZ__UO CopbQqpa|exXLtqr]iQEsOBBDagwRSrYVtyRZeUiHHbsj.CNwF {LIJGXKEtWzuWJ[TVA w]ijeFQpANQax|Lg^dhsVwBH Ngo]{WBKuEKTsG]Ldnt{uFSmN{ ooAsFFmmTtBrFGxoi[Bn_IoX^gMwUPhLg`EsVUnFUAR F{ywvqLWkiDtE_uehxs LeFOhlSSdxxpAkxoMEpE^YYtszasnVQJH koDo{UfZp lGjOSrnoleN\`ZHaKc^BHDgnXAmd`cYKAoFms]Nw w\cQfCDjhty]MF\\eiagjbFQIlrVzqadRoVtc|trZIreUhrakQuOs\RhKan`Wb EQnH[SLbCKFaLHbgrsreZOIbdr^ r[JWZovA{dJ[IDwnXGWJ_uj _`yatSGdu KunyT{s|UeaWIrSrYYtZiE^uK-n_loV^]dKKee^O|iTfiiSvcHnLHeSCDcGdWa`bR[W`D Ap_]\NJc[Kxh^uHz\emc_RAAk\`sjueK\u]aZOxgi[amo_[Woqi.dzB CPfD]I[siDKCnrK'kUfLvtWlPXszbOe |NscrKBtJW^hXjscxagtbGdM kofXv{CHuEwbxiqxFPnSBCYv|E?SD`

---

I give up...

i think this belongs in a different off-topic thread. and who has time to unencrypt that unless theres a benefit from it? hehe

It's a challenge, not a job.

I'm not going to even bother unless you tell me something

What SORT of encryption is it?
Single replacement? Sliding replacement? Seed based adjustment?

Sure, its possible to decrypt something on the order of Enigma or Indigo, but even they had some hints. They also had quite a bit more than one bit to work with.

Let's be honest, with only one encrypted string the best anyone around here is gonna get is a single replacement.

Unless some other characters represent spaces, I'm guessing you have.. um.. something where not only one letter represents one letter of the decrypted string :x
(i'm not all that great with decryption, the most i've learned how to crack is a simple substitution cipher :()

also.. is the "ENC-" at the beginning just outputted by the script at the beginning, or is it an actual part of the encrypted string?

Erm... too hard? You oughta now, how are you gonna decypher it? ;) The only use of encrypting is to pass information to people, and if it's intercepted the interceptors can't read/understand it. So the receivers (unless it's intercepted), must know how to decypher it. I mean, i want to say you this:

But you don't know what it means.

Wrong.

Then, oh great Kaimetsu :rolleyes: what is the reason of encrypting? Or do i understand the meaning wrong :X?

You understand the meaning right, but you fail to comprehend the possible applications. Decryption is not always necessary.

Wow, the controversy.

As I said at the start, the original string is just padded with surplus characters. The actual text can be found in there somewhere.

I'll explain further. A user checksum of 1239 would give one real letter, one fake letter, one real letter, two fake letters, one real letter, nine fake letters, one real letter, one fake letter, one real letter, two fake letters, and so on and so forth.

I should post the program, and in fact I will once I get the opportunity. And get on my home computer where the file is stored. :D

Just because he disagrees with you doesn't mean you have to be b*tchy at him

You're right...
Sorry Kai!
But it's your own fault by being so smart >=O

Okay. Time to elaborate some more on this encryption system.

Let's say I have a checksum of one, and the string "Yohi, world!" (the command for the script would be "\encode 1 Yohi, world!"). It will proceed to pad the string through with fake characters, as in the example below:

NPC Code:

---

(Real characters are in bold.)

ENC-YvoMhliQ,d iwUodrIludI!|

---

Obviously, a more complex checksum will produce more complex results:

NPC Code:

---

/*



\encode 127584 Yohi, all you fun forum people!

(Real characters are in bold.)



*/

ENC-YPoSYhYtZiE^uiKn_lo,

V^]KKe^O|iTiaSlvclHLHSCDc 

GWa`byR[W`DAp_o]\NJu[Kx

f^uHz\m_uRAA\`njueK\]aZOxgif

[oaor_[WoqiduzBCPfmD][iDKCr

 KkUfpLevWolPXszbOpe|Nscl

rKBJW^Xjescxg!b

---

The example attatched at the start of this thread uses an eight-digit checksum, the first four digits of which are 1425. It's tricky to crack, but it'll be interesting to see if you can manage it.

The ENC- prefix is just added by the encoding script in all circumstances and is not part of the encrypted text.

Little hints and tips:

• The random characters range between ASCII values 65 and 124 inclusive, so anything out of that range is guaranteed to be okay.
• I'm sure you guessed this from the previous hint, but all spaces are correct too.
• The original string is preserved character-for-character. If you have the right checksum, you'll get the right thing back. If you get gibberish then you're doing something wrong.
• The first letter in the encoded string - after the ENC- - is always a real letter. For example, in ENC-H4fsdjkhf, the H is guaranteed to be part of the string.

Just as practice, here's a block of encoded data that I've very generously included the checksum for so you can see if you understand the code. The checksum is 1381212 (one real letter, one fake, one real, three fake.. etc) and you can either delete the characters manually or make a script to do it for you. I recommend trying the script. Obviously, whichever way you attempt, you'll need to get rid of the ENC- prefix.

Now that you have a huge wodge of hints, I wish you good luck (again), and happy codebreakin'!

* Edit: I've had some problems using Notepad for this before, but just to point out: there should be no carriage returns (new lines) in the string. If you find some, cut 'em out. Make sure you keep the spaces and things the same, though!

It's easy now that you've given that much information... Well... easy to get the second one. All you need is a way to get the checksum on the first and you're set.

The second one is:
"This is a test string. No, you don't win anything. Sit back down and pay attention." ...obviously

I just figured out the first one's checksum as well. The first time through the post, I didn't even see you had given the digit length and the first 4 digits. Anyway, the checksum becomes 14259735 and gives you the string of "This is a simple text string designed to show how this encryption system operates. It pads out strings with lots of random characters based on a user-defined checksum. Isn't that fun?"

I'm not sure if you expected people to be able to create a script to figure out the checksum... as that's rather impossible, since the script won't have a clue what to look for. As for deciphering the string with the correct checksum, I made a script to do that. If you want me to post it, I will.