Any cryptoanalysts here?

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Any cryptoanalysts here?

Postby loobian » Mon Oct 06, 2003 8:18 am

Hi!

I've been developing a crypting algorithm for sometime...
I am finally done...
The algorithm is symmetric. I am using a table, made from me.

So, anyone good here, willing to try this out? I can publish some simple text here + the table. You try to decode it. If you do- you beat me! If you don't- we'll see what we gonna do.

Thanks!
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Postby Syntaxx » Mon Oct 06, 2003 8:42 am

Well, I'm definitely not a cryptoanalyst, but I'll give it a shot.
C++, because I don't like Java.

In my second year of CCNA classes, hope to be certified after the end of the school year.
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Postby Jimbo » Mon Oct 06, 2003 9:07 am

this could be a contest!!! :P
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Postby RecursiveS » Mon Oct 06, 2003 11:06 am

OK Loobian - bring it on!!!

I'll have a go.....
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Postby loobian » Mon Oct 06, 2003 12:20 pm

Okay, I will need some time to implement it and write the code.
I will publish it here, later today or tomorrow.

We'll have great fun here! :)
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Postby loobian » Mon Oct 06, 2003 12:26 pm

By the way, I recommend to all of you, to read this article:

http://www.hermetic.ch/crypto/intro.htm

It's very good and informative... just to bring you into the subject :) before the real game starts! :)

P.S. I'd be very happy to work with you on breaking this code, even I will know the key... I will be interested in the approaches you guys will use...

I'm so eager to start... :)
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Postby Justin » Tue Oct 07, 2003 2:35 am

Cryptanalysis is sexy. Bring it on. 8)
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Postby loobian » Wed Oct 08, 2003 9:43 am

Hi folks!

I had a math exam today, and I had a lot of work to do for it, that's why I didn't post the data earlier...
I will now write a program in C++ to implement my algorithm (which is pretty amateurs, but it's fun after all!), and when I am ready I will encrypt some text, and will publish it here + the table.
What else would you guys need to work on that? The key?! Sorry, the key is secret! :)
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Postby Justin » Wed Oct 08, 2003 8:36 pm

how about the plain text then ;)
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Postby loobian » Thu Oct 09, 2003 2:57 am

Hi folks!

Here it is, I am ready. I made a C++ program that implements my algorithm.

Here is the table:
Code: Select all
c/y9ojhavw5;ge72?klb06d3t@(^:
ng(5ytu^c02z?ord:fl9!x13pa/@;
z93ihacx0rp^eg6(vtsdmko21!@?/


Here is the header:
Code: Select all
a b c d e f g h i j k l m n o p q r s t u v w x y z <SPACE> . ,


Just to make it clear. The table and the header are connected, but the header is just for you to see which sign to which letter is. i.e. 1-26 signs are for the letters a-z (small letters only!). 27th sign is SPACE, 28th is dot, and 29th sign is comma.

Here is the chipertext:
Code: Select all
ahz^6(hxhtt9ri1(d^0s(0l@z(dysd(@c@x7(y@17m/o0;^/g6b@fhz9@9x0l@9h2b@/9hyz!sh(0t@17m/i6(@cd@ghngs(d^zd(ep@z;crt0bx?@ocs/9t7pyg@/1/160@/@s7@gzi(h^@@7pn1@dxnd@o^lh@lxrm^9@c@ok09h@ahfh@(@c@i0go6@(0/rmld/ozed/d6(xnkh(sreh(dy2d(0o@xoty@@l6/dxcd/160@um1l@(zg(ortp(6o@9khnp0ec/e1(zzc6k09xe(@rpzt@9xzb@cs@vd/@0(d^0g5@9x0l@cs@;6oc@ogrmca@96@dzfe@t6!t@/tn0gl@/31c@/(@l@/160@nth(h3(hydcgc(d^h@og5@6j@9xh(dy2d(dr@avgcsx(ocdx(ird@/m9@0b@10^;@o6d(@l6tk1/0@ce/g6b@9xzb@ldm205@1od/zd(^yzsb@p6m(s^6m;i/9h(xn((t@9xzb@9xh(^ygcad/6a(d^h@7m9(mb@t0^o@c@h(@9xh(3^0(ot9h2b@cs@bxy@scey@zl@9xh(^ygcbx/6a(d^h@vgdmd(ac^h(0/h@bxy@(;zcgdo29@@vg/dxo@oh2b@xhtv6o@@v@10^;@?zpo@g6da@zhghd^s@b6/9h(icaaotygd(3pz@hmps


Okay guys I am expecting your questions. Go break it!
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Postby raimo » Thu Oct 09, 2003 8:33 am

Does the header mean that the plain text consists of the characters a-z, space, dot and comma?

Btw, if there's a secret key which is used to encrypt/decrypt the message then you can publish the C++ source of the algorithm, right? :)
Otherwise people couldn't trust on your algorithm if they didn't know what it is based on. :( Additionally, it would make decrypting the message and finding the secret key much easier for us! ;)
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Postby loobian » Thu Oct 09, 2003 9:40 am

Hi raimo!

Does the header mean that the plain text consists of the characters a-z, space, dot and comma?

- Yes! Simple version is that... :)

Btw, if there's a secret key which is used to encrypt/decrypt the message then you can publish the C++ source of the algorithm, right? :)
Otherwise people couldn't trust on your algorithm if they didn't know what it is based on. :( Additionally, it would make decrypting the message and finding the secret key much easier for us! ;)


The thing is that using bruteforce, and knowing the algorithm you can break it in a matter of hours with regular PC... for example, this text was crypted with 5bit key + one more value that you must know.
But if I give future information, then the algorithm will be known, and breaking this will go to using brute-force and nothing else...
This is plain boring!

What I was interested, was if anybody here can break this WITHOUT knowing the algorithm?

What do you guys think?

After all, I will publish the code here, but I wanted to see if anyone can break it without knowing the encryption algorithm.
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Postby Wizard » Thu Oct 09, 2003 12:07 pm

Curious now, how does the receiver of the message decrypt the code? What is your flow of message passing. Like, suppose I wanted to send you a message, and wanted that to be encrypted. Where would the encryption/decryption keys come from?
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Postby loobian » Thu Oct 09, 2003 12:52 pm

Hi Wizard!

The symmetric algorithms (also know as private-key-algorithms), are not usually used to transfer messages. Or even when you use them for that, the key is usually being given to the other party via a secure channel, or personally. For example, embassadors and politics, who receive encrypted messages with symmetric-algorithms (i.e. like this one), these people have the key delivered personally, usually in a briefcase which is carried by well guarded person.
There is another reason symmetric-algorithms are not usually used for messages: symmetric-algorithms, due to their 'nature', can encrypt much faster than asymmetric-algorithms (also known as public-key algorithsm...like PGP for example). Asymmetric algorithms encrypt a lot of slower, and they are mainly used to encrypt small amount of data. However symmetric algorithms encrypt a lot of faster, and they are more often used to encrypt big amount of data... backups or personal data or such...

I hope this answered your question...
If you still have any doubt- ask me.

Thanks!
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Postby raimo » Thu Oct 09, 2003 12:58 pm

So, is the text encrypted and decrypted using the same algorithm(and key)?
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