Forum

Chipper text with partly source message

Chipper text with partly source message  

  By: Bilajbegovic on Nov. 8, 2012, 8:25 a.m.

Hello,

I have one challenge that I got but I could not solve it.

All I got is this input: "
The coded text is the following:
MDA3MTY4MDAwODg4MDE0NzIwMDAwMzg4MDAwNDQ0MDAwNTEyMDAwMzg4MDI1NjAwMDA3NDg4MDA3Mjk2MDAzNTUyMDAyOTQ0MDAwODMyMDAzNjQ4IzYzNzIyMzI4NjY1NjM1

Plain text contains email address of a person which end on "@aduro.hr".
What is the original plain text message?"

There is no indication what is the algorithm, nor anything else.
What could be the solution?

 Last edited by: Bilajbegovic on Nov. 8, 2012, 8:43 a.m., edited 1 time in total.

Re: Chipper text with partly source message  

  By: Bilajbegovic on Nov. 8, 2012, 8:42 a.m.

What I have found out by now. The chipper text could be braked down to this

MDA3MTY4
MDAwODg4
MDE0NzIw
MDAwMzg4 -> same
MDAwNDQ0
MDAwNTEy
MDAwMzg4 -> same
MDI1NjAw -> MDI starts
MDA3NDg4
MDA3Mjk2
MDAzNTUy
MDAyOTQ0
MDAwODMy
MDAzNjQ4
IzYzNzIy
MzI4NjY1
NjM1

So the most of the message starts with MDA and next 5 letters.
There is 16x 8 letters and 1x4 lettes or 33x4 letter string.
The email address what we know ("@aduro.hr") has one same letter "r" but in the chipper text we have one repetition of the chipper string MDAwMzg4.

What I can assume is the format of the email address. The part before "@aduro.hr" is probably some valid address and probably some name of valid word.
This words usually have the Vowel which is in croatian as well as in english "A E I O U". As there are already letters in "@aduro.hr" "@AdUrO.hr" some of this letters should be repeated in the first part of the email.
Additionally there could be one more interesting thing. As there is repetition of chipper text you have the following string repeated MDAwMzg4. Maybe this is some two letter pars which are repeated.

and the lest 5x4 lettes I have really no idea whit is this since they are not starting with MDA.

Do you have any guess.

Re: Chipper text with partly source message  

  By: Veselovský on Nov. 9, 2012, 1:41 a.m.

It is coded in Base64. After decoding from Base64 I got:
007168000888014720000388000444000512000388025600007488007296003552002944000832003648#63722328665635

There are two numbers separated by #, so it looks like the first number could be a ciphertext and the second number could be a key. But I do not know what type of encryption/cipher was used.

Re: Chipper text with partly source message  

  By: Bilajbegovic on Nov. 9, 2012, 8:55 a.m.

It is coded in Base64. After decoding from Base64 I got:
007168000888014720000388000444000512000388025600007488007296003552002944000832003648#63722328665635

There are two numbers separated by #, so it looks like the first number could be a ciphertext and the second number could be a key. But I do not know what type of encryption/cipher was used.

Uff yes you are right.
But now I'm thinking what it could be.
If I look at the following number coded in hex I got the following

D34EF5EBCD34D3CF3CD35E3BDB4D34D37F3CD34D38E38D34D39D76D34D37F3CD36E7AD34D34EF8F3CD34EF6F7AD34DF9E76D34DBDE38D34D3CDF6D34DFAE3C

D3 4E F5 EB CE B7 EF 6D B7 DB CE BA E7 AD F9
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16

Do you see the problem. Here below is the 16 octets which would be the 128 bits of key.
but there is only 15 bits which is problematic as 120 bits key which is strange. Do you now have any idea what it could be?

Re: Chipper text with partly source message  

  By: Bilajbegovic on Nov. 9, 2012, 8:59 a.m.

and one more thing.
the first number in hex then is this one
D34EF5EB
CD34D3CF
3CD35E3B
DB4D34D3
7F3CD34D
38E38D34
D39D76D3
4D37F3CD
36E7AD34
D34EF8F3
CD34EF6F
7AD34DF9
E76D34DB
DE38D34D
3CDF6D34
DFAE3C

The last number is not 64 bit but like there are two digits less?

Re: Chipper text with partly source message  

  By: argh on Nov. 9, 2012, 2:37 p.m.

It seems to go like that:

Take the base64 decoded string and group it like that:

007168 000888 014720 000388 000444 000512 000388 025600 007488 007296 003552 002944 000832 003648 # 63722328665635

Convert these numbers to hex rsp. binary. One sees that these 16 bit numbers are bytes that were left shifted by some amount. Convert these bytes to ASCII and you get [HTML_REMOVED]posao@aduro.hr[HTML_REMOVED].
I don't know what the number after # means, it could encode the shift amount in some way.

007168 = 0x1c00 = 00_01110000_000000 => p
000888 = 0x0378 = 00000_01101111_000 => o
014720 = 0x3980 = 0_01110011_0000000 => s
000388 = 0x0184 = 000000_01100001_00 => a
000444 = 0x01bc = 000000_01101111_00 => o
000512 = 0x0200 = 00000_01000000_000 => @
000388 = 0x0184 = 000000_01100001_00 => a
025600 = 0x6400 = _01100100_00000000 => d
007488 = 0x1d40 = 00_01110101_000000 => u
007296 = 0x1c80 = 00_0111001_0000000 => r
003552 = 0x0de0 = 000_01101111_00000 => o
002944 = 0x0b80 = 00_001011100_00000 => .
000832 = 0x0340 = 00000_01101000_000 => h
003648 = 0x0e40 = 000_01110010_00000 => r

You know that the application time has expired 3 days ago? [HTML_REMOVED]

Re: Chipper text with partly source message  

  By: Veselovský on Nov. 9, 2012, 3:09 p.m.

I don't know what the number after # means, it could encode the shift amount in some way.

Clearly, it does represent a shift.
quotient(007168,2^6)=112 … "p" in ASCII
quotient(000888,2^3)=111 … "o" in ASCII
quotient(014720,2^7)=115 … "s" in ASCII
quotient(000388,2^2)=97 … "a" in ASCII

so the decryption key is:
63722328665635

Re: Chipper text with partly source message  

  By: argh on Nov. 9, 2012, 3:39 p.m.

Of course! I messed up the spacing in 2 lines, that got me confused…


007488 = 0x1d40 = 00_01110101_000000 => u
007296 = 0x1c80 = 00_01110010_000000 => r
003552 = 0x0de0 = 000_01101111_00000 => o
002944 = 0x0b80 = 00_00101110_000000 => .
000832 = 0x0340 = 00000_01101000_000 => h
003648 = 0x0e40 = 000_01110010_00000 => r

Re: Chipper text with partly source message  

  By: Bilajbegovic on Nov. 9, 2012, 8:23 p.m.

Bravo.
I was looking on the totally wrong way :-).

Re: Chipper text with partly source message  

  By: be on Nov. 10, 2012, 6:40 p.m.

Bravo. :-).

Hello B.

  • Could you tell us, what's the origin of this riddle? Was it a geocaching riddle?

Hello everyone, helping Bilajbegovic.

  • Congratulation. I really enjoyed your excellent cooperation.
  • Maybe it's a good idea to establish an own section in this forum containing only riddles users sent in without formatting them to a challenge. If the riddles are interesting enough like this one, suporters will show up. What do you think?
    Best regards, be

Re: Chipper text with partly source message  

  By: Bilajbegovic on Nov. 10, 2012, 6:49 p.m.

Bravo. :-).

Hello B.

  • Could you tell us, what's the origin of this riddle? Was it a geocaching riddle?

Hi,
This was one riddle for job offering.
I found out it and I was waiting so that job offering end and then I put it on the web. Originally they required PHP program (but it is not important as the way how they calculated).


Currently 18 guests and 0 members are online.
Powered by the CrypTool project
Contact | Privacy | Imprint
© 2009-2024 MysteryTwister team