MysteryTwister C3
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Four levels

Four levels of increasing difficulty: From pen & paper to complex mathematical problems.

Limited attempts

You have only a limited number of attempts to solve each challenge. Be certain of your answer before you submit it.

Be fast

Be fast and earn a place on the Hall of Fame. The first four to solve each challenge will be displayed permanently.

Special Level X

The special level X contains cryptographic problems which are currently not known to have been solved.



Cipher challenges on four levels

 

Level I crypto challenges

Level I Challenges - Pen & Paper

Level I challenges are similar to crossword puzzles from newspapers and can be solved with little cryptographic background. You might not even need a computer for solving level I challenges — all you need is a bit of clever thinking and probably a pen and paper. A program like CrypTool applied to a level I challenge can help reveal the answer within minutes or even seconds, if the necessary algorithms are already built in. Hence, if you are new to cryptography, but nonetheless interested in the mysterious topic of cryptanalysis, give the level I challenges a try. You will almost assuredly meet quickly with success.
 
Level II crypto challenges

Level II Challenges - Programming skills required

Level II challenges require some background knowledge in cryptology and usually some computational power. Additionally, you may require tools that are not available in such convenient packages like CrypTool, OpenSSL or Sage. Therefore, you must first thoroughly understand the problem in order to write a computer program, which helps you getting along. It could take hours or even days to solve a level II challenge. Hence, if you consider yourself well-armed with cryptologic knowledge (such as if you are a university student in a cryptographic course), give the level II challenges a try. Success may not come easily, but it will be a worthwhile endeavor.
 
Level III crypto challenges

Level III Challenges - Extensive computing power recommended

Level III challenges require a thorough background in cryptanalysis and usually significant computational power as well. The problems in this level represent current research topics that are believed to be very difficult to solve. Thus, practical solutions may not even exist and ready-to-run tools almost certainly do not. The methodology to solve some of these challenges may already be known, but it may require such a huge amount of computational power that only a large group of people working together in a distributed system could obtain the solution. Challenges in this category mark the thin line between algorithms that are still secure and those that are not. Solving them may take weeks or even several months. Hence, challenges in this level are intended for entire research groups with many experts in cryptanalysis, programming, and distributed systems. Success cannot be guaranteed, but if you are the first to successfully solve one of these challenges, it probably would catch the attention of the scientific community. Of course, it still remains up to you to publish or present any such scientific techniques and results.
 
Level X crypto challenges

Level X Challenges - Unsolved ciphers

Most level X challenges contain problems that have remained unsolved for a long time. The fact that they have been unsolved regardless of numerous attempts suggests these challenges being hard. However, a simple idea can probably reduce the difficulty of it to a simple level I challenge — currently it is just unknown if and how they can be solved. Of course such a challenge cannot be solved with a simple codeword, since even we (the respective author and the MTC3 team) do not know the solution (the plaintext, the original message or the approach). So if you discover a promising solution you should either contact the author or the MTC3 team. Furthermore, you can publish your findings in a scientific journal such as Cryptologia or Journal of Cryptology.

 

Additionally, you may require tools that are not available in a convenient package like CrypTool.


All Challenges (292)

Ordered by date posted, the most recent appear first.

Spirale — Part 3

[allard-03] - 3 users already solved this challenge.
 
 
 

Spirale is a OTP cipher designed to be simply performed by hand.
Part 3 is a ciphertext-only challenge with a 949-letter ciphertext.
In this part, two of the four keys are equal to the keys of the first two parts.
Read more...

Click here to get to the corresponding forum topic to share your opinion.
Click here to download the challenge.
Click here to download the additional file of the challenge.

Author: This email address is being protected from spambots. You need JavaScript enabled to view it.
Published on: 2015-08-23 19:08
Maximum number of attempts for this challenge: 15

All successful users of this challenge

Rank User (#3) Achieved points (Global score) y-m-d - h:m:s

S Combes (jerva) 1378 (99132) 2015-09-13 15:43:29
J-L Morel (Rossignol) 1143 (29425) 2017-01-19 15:27:30
George Lasry (george4096) 1129 (302230) 2017-08-21 21:46:21
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Spirale — Part 2

[allard-02] - 3 users already solved this challenge.
 
 
 

Spirale is a OTP cipher designed to be simply performed by hand.
Part 2 is a ciphertext-only challenge with a 659-letter ciphertext.
This part uses the same four keys for encryption as part 1 does.
Read more...

Click here to get to the corresponding forum topic to share your opinion.
Click here to download the challenge.
Click here to download the additional file of the challenge.

Author: This email address is being protected from spambots. You need JavaScript enabled to view it.
Published on: 2015-08-23 19:05
Maximum number of attempts for this challenge: 15

All successful users of this challenge

Rank User (#3) Achieved points (Global score) y-m-d - h:m:s

S Combes (jerva) 1378 (99132) 2015-09-12 21:15:06
J-L Morel (Rossignol) 1143 (29425) 2017-01-19 15:23:12
George Lasry (george4096) 1129 (302230) 2017-08-21 21:06:46
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Spirale — Part 1

[allard-01] - 3 users already solved this challenge, 2 are working on it.
 
 
 

Spirale is a OTP cipher designed to be simple to implement by hand. It is resilient to errors as they have only a local effect without obscuring all the ciphertext.
Part 1 is a partly-known plaintext challenge with a 314-letter ciphertext. The first 75 letters of the plaintext are known.
Part 2 of this series uses the same four keys as this one.
Read more...

Click here to get to the corresponding forum topic to share your opinion.
Click here to download the challenge.
Click here to download the additional file of the challenge.

Author: This email address is being protected from spambots. You need JavaScript enabled to view it.
Published on: 2015-08-23 19:04
Maximum number of attempts for this challenge: 15

All successful users of this challenge

Rank User (#3) Achieved points (Global score) y-m-d - h:m:s

S Combes (jerva) 1378 (99132) 2015-09-12 21:12:42
J-L Morel (Rossignol) 1143 (29425) 2017-01-19 15:14:20
George Lasry (george4096) 1129 (302230) 2017-08-21 20:56:27
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Flawed Usage of a OTP Cipher by the BND

[drobick-04] - 12 users already solved this challenge.
 
 
 

During the cold war the foreign intelligence agency of Germany established so-called stay-behind units. Their radio messages were encrypted by a OTP method, but the keys were used multiple times.
This challenge is about the effect of this multiple usage on the security of the method. You are given 5 messages, all encrypted with the same key.
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Author: This email address is being protected from spambots. You need JavaScript enabled to view it.
Published on: 2015-08-23 19:00
Maximum number of attempts for this challenge: 15

All successful users of this challenge

Rank User (#12) Achieved points (Global score) y-m-d - h:m:s

Armin Krauss (argh) 1725 (188214) 2015-08-26 17:13:36
Kurt Gebauer (Yokozuna) 1576 (177433) 2015-08-28 22:20:36
Alain (Integral) 1456 (207924) 2015-09-04 16:37:12
Bart den Hartog (Bart13) 1398 (144081) 2015-09-10 14:30:56
#5 Julia Bernotat (El Greco ) 1337 (81129) 2015-09-21 21:32:23
#6 Robert (rm) 1292 (56475) 2015-10-08 21:06:29
#7 Matthias Kotzerke (Esdeath) 1182 (4004) 2016-03-30 19:45:17
#8 Em Doulgerakis (Greko) 1172 (124033) 2016-05-16 09:35:38
#9 Alain Collignon (vexilla72) 1152 (90800) 2016-10-10 18:28:06
#10 D3d4lu5 (D3d4lu5) 1130 (297709) 2017-08-08 22:49:04
#11 Nicolas (nicosPavlov) 1120 (151166) 2018-04-01 11:44:13
#12 Dominik M. (Sgt. Pepper) 1117 (97919) 2018-06-21 23:00:27
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Double-Column Transposition/Granit — Part 3

[drobick-03] - 0 users already solved this challenge.
 
 
 

This challenge series is about the GRANIT cipher, a method that can be done manually. It has been used for instance by the former GDR spy Günter Guillaume till about 1960.
Part 1, 2 and 3 of this series use the same keyword for generating the key matrix, but different permutation keys. This part has a ciphertext-only challenge and the ciphertext has 80 characters.
Read more...

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Author: This email address is being protected from spambots. You need JavaScript enabled to view it.
Published on: 2015-07-01 18:23
Maximum number of attempts for this challenge: 10

All successful users of this challenge

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   +++    [13:37 - 19.09.2019] h4rdl0ck solved the Level II challenge 'Factorization Cipher — Part 2'    +++    [07:08 - 19.09.2019] Bart13 solved the Level II challenge 'Hilly — Part 1'    +++    [23:59 - 18.09.2019] Byqq!T3qmxxZfRir solved the Level I challenge 'Number Sequence'    +++    [14:21 - 18.09.2019] h4rdl0ck solved the Level I challenge 'Factorization Cipher — Part 1'    +++    [14:15 - 18.09.2019] lim0n solved the Level I challenge 'Image Noise'    +++