Level I Challenges

92 published challenges (in level I), sorted by:
The Syllabary Cipher – Part 1
Description
The Syllabary cipher seems to be just another substitution cipher, but is it? Find out and solve its mystery!
Solve this challenge
179 users have already solved this challenge, 31 are working on it.
You need to be logged in to solve this challenge.
Merkle-Hellman Knapsack Challenge - Part 1
Description
The legendary Merkle-Hellman Knapsack cryptosystem is not suitable for hiking, but it is considered a pioneer of asymmetric cryptography. Can you crack the ciphertext?
Solve this challenge
61 users have already solved this challenge, 11 are working on it.
You need to be logged in to solve this challenge.
Alberti Challenge — Part 1
Description
This challenge is about one of the oldest polyalphabetic ciphers. Can you crack this centuries-old puzzle?
Solve this challenge
131 users have already solved this challenge, 19 are working on it.
You need to be logged in to solve this challenge.
Wheatstone Cryptograph — Part 1
Description
The Wheatstone Cryptograph is a simple device that resembles a clock with two hands. For each hand there is a ring of symbols. Are you able to decrypt the given ciphertext?
Solve this challenge
102 users have already solved this challenge, 8 are working on it.
You need to be logged in to solve this challenge.
Find the right route — Part 3
Description
This series deals with a grid — a basic tool cryptographers use to separate sequences of data into columns and rows. In this challenge you are given three grids where the first grid gives you hints to reveal the plaintext of the second grid. Are you able to find the right route?
Solve this challenge
32 users have already solved this challenge, 5 are working on it.
You need to be logged in to solve this challenge.
Find the right route — Part 2
Description
This series deals with a grid — a basic tool cryptographers use to separate sequences of data into columns and rows. In this challenge you are given four grids where the first grid gives you hints to reveal the plaintext of the second grid. Are you able to find the right route?
Solve this challenge
33 users have already solved this challenge, 3 are working on it.
You need to be logged in to solve this challenge.
Find the right route — Part 1
Description
This series deals with a grid — a basic tool cryptographers use to separate sequences of data into columns and rows. In this challenge you are given two grids where the first grid gives you hints to reveal the plaintext of the second grid. Are you able to find the right route?
Solve this challenge
90 users have already solved this challenge, 19 are working on it.
You need to be logged in to solve this challenge.
Lightweight Introduction to Lattices — Part 2
Description
Lattice-based cryptography schemes are relevant for current post-quantum cryptography research. This challenge series accompanies the basic theory from a chapter of the CrypTool Book called "LIGHTWEIGHT INTRODUCTION TO LATTICES". This part of the challenge series uses vectors to hide a famous quote in modern art. Can you reveal it?
Solve this challenge
40 users have already solved this challenge, 4 are working on it.
You need to be logged in to solve this challenge.
Lightweight Introduction to Lattices — Part 1
Description
Lattice-based cryptography schemes are relevant for current post-quantum cryptography research. This challenge series accompanies the basic theory from a chapter of the CrypTool Book called "LIGHTWEIGHT INTRODUCTION TO LATTICES". In this part of the challenge series we introduce systems of linear equations to find a hidden message in a picture.
Solve this challenge
56 users have already solved this challenge, 5 are working on it.
You need to be logged in to solve this challenge.
Polyhomophonic Substitution — Part 1
Description
This part of the challenge series is a warm-up with homophonic substitution. In a homophonic substitution cipher, there are more than one ciphertext symbol for each plaintext symbol. The key is a mapping.
Solve this challenge
53 users have already solved this challenge, 7 are working on it.
You need to be logged in to solve this challenge.
Cryptanalysis Hacking Puzzles — Part 2
Description
Solving this challenge is not as hard as finding the needle in a haystack, isn't it?
Solve this challenge
203 users have already solved this challenge, 38 are working on it.
You need to be logged in to solve this challenge.
Cryptanalysis Hacking Puzzles — Part 1
Description
Three messages were delivered — two encrypted, one in clear. Can you solve the puzzle?
Solve this challenge
33 users have already solved this challenge, 39 are working on it.
You need to be logged in to solve this challenge.
Autokey Cipher
Description
The autokey cipher uses only a short keyword and the plaintext to encrypt messages. Are you able to break the given ciphertext?
Solve this challenge
188 users have already solved this challenge, 13 are working on it.
You need to be logged in to solve this challenge.
Modular Sequences
Description
What do you know about modular sequences? Work it out.
Solve this challenge
79 users have already solved this challenge, 36 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 10
Description
How many experience points does Thomas need to reach the 200th level of his new computer game?
Solve this challenge
118 users have already solved this challenge, 22 are working on it.
You need to be logged in to solve this challenge.
Advent-Challenge — Part 1
Description
Little Anna has forgotten how to decrypt her ciphertext. Can you come up to her pre-Christmas wish?
Solve this challenge
498 users have already solved this challenge, 26 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 9
Description
Are you able to crack the password of Radomil and find the missing 5 digits?
Solve this challenge
120 users have already solved this challenge, 67 are working on it.
You need to be logged in to solve this challenge.
New Year's Greetings — Part 4
Description
This series consists of five parts which are based on each other and that will be getting more and more complicated with each part. This part is the actual challenge and tells you the New Year's greeting of the author.
Solve this challenge
44 users have already solved this challenge, 13 are working on it.
You need to be logged in to solve this challenge.
New Year's Greetings — Part 3
Description
This series consists of five parts which are based on each other and that will be getting more and more complicated with each part. Part 4 contains a little New Year's greeting of the author and part 5 teaches us something about the weaknesses of this method. Part 3 adds another modification.
Solve this challenge
47 users have already solved this challenge, 4 are working on it.
You need to be logged in to solve this challenge.
New Year's Greetings — Part 2
Description
This series consists of five parts which are based on each other and that will be getting more and more complicated with each part. Part 4 contains a little New Year's greeting of the author and part 5 teaches us something about the weaknesses of this method. Part 2 modifies the encryption of part 1 a little bit.
Solve this challenge
49 users have already solved this challenge, 3 are working on it.
You need to be logged in to solve this challenge.
New Year's Greetings — Part 1
Description
This series consists of five parts which are based on each other and that will be getting more and more complicated with each part. Part 4 contains a little New Year's greeting of the author and part 5 teaches us something about the weaknesses of this method. Part 1 is the easiest part of this series.
Solve this challenge
54 users have already solved this challenge, 19 are working on it.
You need to be logged in to solve this challenge.
Image Noise
Description
Both images in this challenge seem to contain no information at all. Or do they trick us? Find the secret message.
Solve this challenge
161 users have already solved this challenge, 25 are working on it.
You need to be logged in to solve this challenge.
News from Castle Mansfeld
Description
The story of the simple bookseller Paul from Eisleben and his beloved from the near Castle Mansfeld will be continued: A second postcard has been found. Can you decipher the encrypted message?
Solve this challenge
59 users have already solved this challenge, 1 is working on it.
You need to be logged in to solve this challenge.
Weakened Granit — Part 1
Description
The challenges for the simplified GRANIT cipher, a method that can be done manually, serve as an exercise and use an intentionally simplified version of GRANIT. Part 1 is a ciphertext-only challenge for which both permutation keys are known.
Solve this challenge
49 users have already solved this challenge, 5 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 8
Description
How are the numbers interconnected? Can you find the three missing numbers?
Solve this challenge
405 users have already solved this challenge, 33 are working on it.
You need to be logged in to solve this challenge.
A hidden word — Part 2
Description
A friend of yours has given you the following text which contains only X and Y characters. He claims that this text contains a codeword. Can you find it?
Solve this challenge
113 users have already solved this challenge, 51 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 7
Description
How are the numbers linked? Can you find the two missing numbers?
Solve this challenge
97 users have already solved this challenge, 37 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 6
Description
How are the numbers linked? Can you find the two missing numbers?
Solve this challenge
163 users have already solved this challenge, 20 are working on it.
You need to be logged in to solve this challenge.
M-138 — Part 1
Description
This is the beginner's challenge in a series about M-138, a manual cipher of the US army which has been relatively save at the beginning of world war 2nd. Part 1 of the series is a ciphertext-only challenge whose key is largely known.
Solve this challenge
224 users have already solved this challenge, 16 are working on it.
You need to be logged in to solve this challenge.
The Last Note
Description
You can find a short encrypted note at the end of the novel "Die achte Offenbarung" by Karl Olsberg. Decrypt the secret message!
Solve this challenge
99 users have already solved this challenge, 22 are working on it.
You need to be logged in to solve this challenge.
Heartbleed — Part 2
Description
This challenge is based on the Heartbleed bug in OpenSSL discovered in April 2014. Attack a server which is specifically prepared to be vulnerable to the Heartbleed bug. Please note that it is necessary to solve Part 1 first. !!! We had to take off this challenge, as our firewall doesn't allow flawed servers any more -- even if this flaw was offered by will for training and within a sandbox. !!!
Solve this challenge
60 users have already solved this challenge, 12 are working on it.
You need to be logged in to solve this challenge.
The solution for this challenge was made public on May 17, 2022, 6:32 p.m., and thus it is no longer possible to get points for this challenge. However, you can still solve it and enter a solution for this challenge.
Heartbleed — Part 1
Description
This challenge is based on the Heartbleed Bug in OpenSSL discovered in April 2014. Attack a server provided by the group for Privacy and Compliance with the Research Institute Cyber Defence (CODE) at Bundeswehr University Munich, which is specifically prepared to be vulnerable to the Heartbleed bug. !!! We had to take off this challenge, as our firewall doesn't allow flawed servers any more -- even if this flaw was offered by will for training and within a sandbox. !!!
Solve this challenge
90 users have already solved this challenge, 21 are working on it.
You need to be logged in to solve this challenge.
The solution for this challenge was made public on May 17, 2022, 6:32 p.m., and thus it is no longer possible to get points for this challenge. However, you can still solve it and enter a solution for this challenge.
Enigma Messages with Repeated Letters — Part 5
Description
In this part of this series of Enigma challenges, a plaintext message consisting of three letters which are repeated several times has been encrypted by the Enigma I. What are the first three letters of the plaintext? Show details…Hide details…
Solve this challenge
82 users have already solved this challenge, 9 are working on it.
You need to be logged in to solve this challenge.
Enigma Messages with Repeated Letters — Part 4
Description
In this part of this series of Enigma challenges, a plaintext message consisting of three letters which are repeated several times has been encrypted by the Enigma I. What was the setting of the Enigma rotors?
Solve this challenge
78 users have already solved this challenge, 3 are working on it.
You need to be logged in to solve this challenge.
Enigma Messages with Repeated Letters — Part 3
Description
In this part of this series of Enigma challenges, a plaintext message consisting of two letters which are repeated several times has been encrypted by the Enigma I. What was the setting of the Enigma rotors?
Solve this challenge
86 users have already solved this challenge, 3 are working on it.
You need to be logged in to solve this challenge.
Enigma Messages with Repeated Letters — Part 2
Description
In this part of this series of Enigma challenges, a plaintext message consisting of one letter which is repeated several times has been encrypted by the Enigma I. What was the setting of the Enigma rotors?
Solve this challenge
86 users have already solved this challenge, 17 are working on it.
You need to be logged in to solve this challenge.
Trifid Cipher
Description
Two scatterbrained professors exchange messages that have been encrypted with the Trifid cipher. Unfortunately, one of them lost the second of three layers. Will he nevertheless be able to decrypt the message he received from his colleague?
Solve this challenge
128 users have already solved this challenge, 8 are working on it.
You need to be logged in to solve this challenge.
Enigma Messages with Repeated Letters — Part 1
Description
In this part of this series of Enigma challenges, a plaintext message consisting of one letter which is repeated several times has been encrypted by the Enigma I. What is the letter we are looking for?
Solve this challenge
179 users have already solved this challenge, 35 are working on it.
You need to be logged in to solve this challenge.
Hill Cipher with Sudoku Key
Description
You find a note with strange characters and an unsolved Sudoku on your brother's desk. You are curious and would like to find out what your brother is working on. Can you decrypt the note using the Sudoku?
Solve this challenge
107 users have already solved this challenge, 5 are working on it.
You need to be logged in to solve this challenge.
From Russia with Love
Description
Sarah and Igor are exchange students. Sarah lives in Moscow while Igor is in Berlin. To keep their little secrets confidential, they encrypt their emails. Decrypt the message to find out what Sarah wrote this time.
Solve this challenge
293 users have already solved this challenge, 33 are working on it.
You need to be logged in to solve this challenge.
Nils away on travel
Description
Nils would like to go on a journey and has given you a note with information about his destination. The note is encrypted. Can you find out where he would like to go?
Solve this challenge
175 users have already solved this challenge, 15 are working on it.
You need to be logged in to solve this challenge.
Snow White and the seven dwarfs
Description
The seven dwarfs are missing. Snow White however finds a file, which contains useful information steganographically hidden. Help her to find the dwarfs.
Solve this challenge
295 users have already solved this challenge, 86 are working on it.
You need to be logged in to solve this challenge.
Reserve Hand Procedure — Part 1
Description
The reserve hand procedure has been used as a replacement of the Enigma machine. Can you decrypt the given ciphertext?
Solve this challenge
195 users have already solved this challenge, 11 are working on it.
You need to be logged in to solve this challenge.
Multilingual Monoalphabetic Substitution
Description
The plaintext consists of English, French, German and Italian words. Can you identify the four sentences after you have solved the monoalphabetic substitution?
Solve this challenge
79 users have already solved this challenge, 6 are working on it.
You need to be logged in to solve this challenge.
Cascading Encryption — Part 1/3
Description
Can you break this cascading encryption that consists of a combination of substitution and transposition? The solution contains important information for the next parts.
Solve this challenge
73 users have already solved this challenge, 2 are working on it.
You need to be logged in to solve this challenge.
Enigma Messages
Description
Can you find the plaintext using 26 Engima ciphertexts that have been encrypted with different rotors and different initial settings?
Solve this challenge
82 users have already solved this challenge, 4 are working on it.
You need to be logged in to solve this challenge.
Playfair with hints about the grid
Description
In this challenge, only fragments of the grid used for a Playfair encryption are given. Are you able to reconstruct the matrix and decrypt the message?
Solve this challenge
119 users have already solved this challenge, 6 are working on it.
You need to be logged in to solve this challenge.
A hidden word
Description
This PDF file is supposed to contain a hidden codeword. Can you find it?
Solve this challenge
858 users have already solved this challenge, 165 are working on it.
You need to be logged in to solve this challenge.
Strange Message from Thessaloniki
Description
This postcard from Thessaloniki was written in German in 1897. The encrypted text can either be considered as message from the sailor Fritz to his wife at home, or as a note regarding spionage activities. Can you determine the codeword that was used to request secret information?
Solve this challenge
51 users have already solved this challenge, 5 are working on it.
You need to be logged in to solve this challenge.
Recycled One-Time Pad
Description
Can you decrypt the three military messages?
Solve this challenge
69 users have already solved this challenge, 13 are working on it.
You need to be logged in to solve this challenge.
Beaver Code
Description
The Beaver Code is a transposition cipher. Apart from the solution of this challenge, can you find a formula for any given ciphertext length, which generates the permutation needed to decrypt the ciphertext?
Solve this challenge
1214 users have already solved this challenge, 45 are working on it.
You need to be logged in to solve this challenge.
Letter to the Templars — Part 2
Description
Can you decrypt the second part of the letter to the Templars as effortlessly as the first one?
Solve this challenge
839 users have already solved this challenge, 12 are working on it.
You need to be logged in to solve this challenge.
Letter to the Templars — Part 1
Description
After the Order of the Templar has become very powerful, enviers try to crush it. The knights receive an encrypted letter but the key does not arrive. Does this letter contain the warning that would have saved the knights from being arrested?
Solve this challenge
1044 users have already solved this challenge, 43 are working on it.
You need to be logged in to solve this challenge.
An 'unhearable' message
Description
Your friend sent you an audio file that contains only a strange melody. In the email, your friend writes that the file contains a message encoded by a variant of Morse code. Can you find out how you can hear the Morse code?
Solve this challenge
41 users have already solved this challenge, 19 are working on it.
You need to be logged in to solve this challenge.
How do you become a big cryptographer?
Description
You are invited to a job interview for the job of a cryptographer. Can you pass the first selection round?
Solve this challenge
230 users have already solved this challenge, 106 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 5
Description
How are the numbers linked? Can you find the three missing numbers?
Solve this challenge
104 users have already solved this challenge, 130 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 4
Description
Can you find the link between these numbers?
Solve this challenge
849 users have already solved this challenge, 23 are working on it.
You need to be logged in to solve this challenge.
¿No Hablas Español? No problemo!
Description
You don't speak Spanish? No Problem! Try to decrypt a ciphertext in a foreign language without knowledge of that language.
Solve this challenge
168 users have already solved this challenge, 18 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 3
Description
This number sequence is cyclic. Can you find out the fifth and sixth number?
Solve this challenge
1027 users have already solved this challenge, 109 are working on it.
You need to be logged in to solve this challenge.
The Book Code: A Challenge for Bookworms
Description
In order to decrypt the intercepted letter addressed to your neighbor, you need to find out which document has been used to encode the message with the book code.
Solve this challenge
153 users have already solved this challenge, 27 are working on it.
You need to be logged in to solve this challenge.
ECDH-Key Exchange for Beginners
Description
Alice and Bob would like to agree upon a shared key. They use an Elliptic Curve Diffie-Hellman (ECDH) key-exchange protocol. Try to reproduce the steps that are necessary to calculate the key and to decrypt Bob's message.
Solve this challenge
100 users have already solved this challenge, 2 are working on it.
You need to be logged in to solve this challenge.
Monoalphabetic substitution with camouflage — Part 4
Description
Alice and Bob use the cipher as it had been described in part 3 of this challenge. Due to an error one message has been encrypted and sent twice. Does this help you to find out the shared key and enables you to decrypt a third message easily?
Solve this challenge
51 users have already solved this challenge, 5 are working on it.
You need to be logged in to solve this challenge.
Monoalphabetic substitution with camouflage — Part 1
Description
It is not difficult to break a monoalphabetic substitution but in this challenge an additional camouflage alphabet causes confusion.
Solve this challenge
66 users have already solved this challenge, 8 are working on it.
You need to be logged in to solve this challenge.
Factorization Cipher — Part 1
Description
With the help of 7 pairs of plaintext-ciphertext you have to find out how this factorization cipher works and then decrypt a ciphertext.
Solve this challenge
512 users have already solved this challenge, 17 are working on it.
You need to be logged in to solve this challenge.
Turing Bombe Enigma I
Description
You intercepted two ENIGMA I messages. Both are dated from the same day. Use a Turing Bombe to find out the key of the day and decipher the solution.
Solve this challenge
73 users have already solved this challenge, 3 are working on it.
You need to be logged in to solve this challenge.
An Invisible Message
Description
A friend of yours sent you a file that seems to be empty. Was it just a mistake or is there a secret to reveal?
Solve this challenge
61 users have already solved this challenge, 18 are working on it.
You need to be logged in to solve this challenge.
Grille Cipher
Description
You need to reconstruct some fields of the grille to decrypt the message written on an old note.
Solve this challenge
499 users have already solved this challenge, 41 are working on it.
You need to be logged in to solve this challenge.
Double Columnar Transposition
Description
Asterix and Obelix besiege Rome. They just happened to find an encrypted message but instead of the common Caesar Cipher the Romans used a new method. Can you decrypt the message?
Solve this challenge
118 users have already solved this challenge, 4 are working on it.
You need to be logged in to solve this challenge.
Affine Codes / Modulo Arithmetic with N / Extended Euclid
Description
Two girls want to communicate in a secret way using the „affine cipher“. Transform the encryption rule into the decryption rule and turn in the plaintext of the example.
Solve this challenge
602 users have already solved this challenge, 11 are working on it.
You need to be logged in to solve this challenge.
Pigpen with a twist — Part 1
Description
In this challenge the rotational relationship between the Pigpen symbols are used to create a new cipher. In this part the well-known key squares are used as a warm up.
Solve this challenge
156 users have already solved this challenge, 7 are working on it.
You need to be logged in to solve this challenge.
Modified Caesar Cipher
Description
The Caesar Chiper is rather simple. But in this challenge it is used with a different alphabet and a modified way of shifting the letters.
Solve this challenge
233 users have already solved this challenge, 61 are working on it.
You need to be logged in to solve this challenge.
ADFGVX — Part 2
Description
A pair of plaintext and the corresponding ciphertext encrypted with the ADFGVX cipher ist given. Can you reveal the substitution and transposition key used in this example?
Solve this challenge
126 users have already solved this challenge, 8 are working on it.
You need to be logged in to solve this challenge.
ADFGVX — Part 1
Description
A small ciphertext encrypted with the ADFGVX cipher, which has been used during World War I, is given. Are you able to reveal the plaintext message?
Solve this challenge
121 users have already solved this challenge, 17 are working on it.
You need to be logged in to solve this challenge.
Number Sequence — Part 2
Description
This sequence is infinite, the first 9 numbers are given. What are the 10th and 11th number?
Solve this challenge
2143 users have already solved this challenge, 486 are working on it.
You need to be logged in to solve this challenge.
Music Code — Part 1
Description
A piece of music is given as mp3 file and in music notation. The notes represent a secret message, which was encrypted with two classic methods. In part 1 of this challenge you have to solve the first of these methods. Thereafter, you can set out to solve part 2 (which is in level 2).
Solve this challenge
43 users have already solved this challenge, 30 are working on it.
You need to be logged in to solve this challenge.
Post-Quantum Cryptography: Unbalanced Oil and Vinegar System — Part 1
Description
By the time quantum computers exist, the actual signing algorithms are not secure anymore. Then one can switch e.g. to so-called "Unbalanced Oil and Vinegar" systems. It is your challenge to break a simplified version of such a system today already.
Solve this challenge
100 users have already solved this challenge, 2 are working on it.
You need to be logged in to solve this challenge.
Kaskade-S/T — Part 1
Description
A friend sends you a cipher designed by him and asks you to discover the used key, using a given plaintext and the corresponding ciphertext.
Solve this challenge
107 users have already solved this challenge, 7 are working on it.
You need to be logged in to solve this challenge.
Playfair Encryption
Description
In this challenge you shall break the Playfair encryption which was used by the British forces in the Crimean War and in World War I, among others.
Solve this challenge
128 users have already solved this challenge, 11 are working on it.
You need to be logged in to solve this challenge.
Original Caesar Cipher
Description
In this challenge you shall break the Caesar encryption in its original form.
Solve this challenge
3069 users have already solved this challenge, 146 are working on it.
You need to be logged in to solve this challenge.
Enigma Combinatorics
Description
The Enigma is an electro-mechanical rotor machine used for encryption and decryption. One main part of the Enigma is changeable rotors. This challenge deals with the calculation of the key space.
Solve this challenge
107 users have already solved this challenge, 65 are working on it.
You need to be logged in to solve this challenge.
One-Time Pad with Flaws
Description
The "Three Investigators" heard that it was possible to create truly unbreakable cipher texts if you linked a stream of true random numbers to the plaintext (one-time pad). However this random stream must be incalculable for outsiders. Do you think you can, nevertheless, decrypt an eavesdropped encrypted message from the "Three Investigators"?
Solve this challenge
315 users have already solved this challenge, 23 are working on it.
You need to be logged in to solve this challenge.
Molehunt (Part 2/3)
Description
This is part 2 of a 3-part challenge regarding the classical transposition. You can solve this challenge with pen and paper as well as with different software programs. To create the ciphertext the plaintext was first encrypted with a classical shift cipher. The result of this encryption was then further encrypted with a columnar transposition with a key length of less than 10 characters.
Solve this challenge
150 users have already solved this challenge, 7 are working on it.
You need to be logged in to solve this challenge.
Molehunt (Part 1/3)
Description
This is part 1 of a 3-part challenge regarding the classical transposition. You can solve this challenge with pen and paper as well as with adequate software programs (e.g. CrypTool 2). With this irregular columnar tranposition a key length greater than 10 was used.
Solve this challenge
159 users have already solved this challenge, 11 are working on it.
You need to be logged in to solve this challenge.
A modified homophonic cipher with reduced alphabets — Part 2
Description
Homophonic substitution using 5 ciphertext characters for a binary cleartext alphabet. This challenge can be solved with paper & pencil.
Solve this challenge
343 users have already solved this challenge, 8 are working on it.
You need to be logged in to solve this challenge.
A modified homophonic cipher with reduced alphabets — Part 1
Description
Homophonic substitution using 3 ciphertext characters for a binary cleartext alphabet. This challenge can be solved with paper & pencil.
Solve this challenge
398 users have already solved this challenge, 76 are working on it.
You need to be logged in to solve this challenge.
Caesar Encryption
Description
The Caesar encryption, a very simple example of a monoalphabetic substitution.
Solve this challenge
1467 users have already solved this challenge, 790 are working on it.
You need to be logged in to solve this challenge.
Zodiac Cipher
Description
In the late 1960s the so called Zodiac killer used a homophonic substitution encryption to encrypt letters to the police and the press. This challenge is inspired by the solved Zodiac-408 problem and the unsolved Zodiac-340 problem. Hint: Provide the codeword in capital letters.
Solve this challenge
101 users have already solved this challenge, 39 are working on it.
You need to be logged in to solve this challenge.
Monoalphabetic Substitution
Description
This is a famous speech of a German soccer star - including a mistake. The codeword consists of 2 words, one after the other with no space. The first is the password used to encrypt the plaintext, and the second is the mistake in the decrypted text. (The plaintext is in German.)
Solve this challenge
556 users have already solved this challenge, 184 are working on it.
You need to be logged in to solve this challenge.
Number Sequence
Description
This sequence is infinite, but you may recognize it after just 13 numbers. What is the 14th number? Please type in the numeric expression of the number.
Solve this challenge
4353 users have already solved this challenge, 429 are working on it.
You need to be logged in to solve this challenge.
Letter from the Alleged Countess Julie von Ortenburg
Description
In 1806, the young countess Julie finds a dress with an old enciphered letter in a pouch. It reveals a secret of one of Julie's ancestors. Can you break the cipher? The codeword for this challenge is the last word of the letter (all uppercase).
Solve this challenge
181 users have already solved this challenge, 20 are working on it.
You need to be logged in to solve this challenge.
A Secret Message from Castle Mansfeld
Description
In September 1902, a book seller named Paul Winkler received a postcard in cipher. Sent from the nearby Mansfeld castle, it appears that a young lady wants to meet with Paul – secretly. Find the name of the young lady and submit it as the codeword for this challenge. Use only capital letters.
Solve this challenge
131 users have already solved this challenge, 19 are working on it.
You need to be logged in to solve this challenge.
Classical Ciphers^3
Description
This challenge contains three messages encrypted with classical ciphers. You will need break each of the ciphers and take note of the three codewords. When you have all three codewords, submit them in the form "codeword1-codeword2-codeword3". Please note that the codewords are case sensitive and you have only 5 trials to find the correct solution. The MTC3 team wishes everybody much success and fun in finding the correct solution.
Solve this challenge
188 users have already solved this challenge, 17 are working on it.
You need to be logged in to solve this challenge.
Currently 15 guests and 0 members are online.
Powered by the CrypTool project
Contact | Privacy | Imprint
© 2009-2023 MysteryTwister team