On May 2, 2023, 4:11 p.m.
Unlock the secrets of the Hutton cipher, a pen-and-paper cipher that has baffled cryptographers since 2018. Can you crack the ciphertext?
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On March 27, 2023, 10:05 a.m.
The Josse cipher is a polyalphabetic cipher from the time of the Franco-Prussian War. Its description was lost. It was only rediscovered and published in 2020.…
On Feb. 25, 2023, 1:29 a.m.
The Josse cipher is a polyalphabetic cipher from the time of the Franco-Prussian War. Its description was lost. It was only rediscovered and published in 2020.…
On Feb. 10, 2023, 8:47 a.m.
The Josse cipher is a polyalphabetic cipher from the time of the Franco-Prussian War. Its description was lost. It was only rediscovered and published in 2020.…
On Dec. 30, 2022, 12:59 p.m.
The Lorenz SZ42, codenamed Tunny, was a German teleprinter encryption device used during WW2. This is the fourteenth challenge in a series of 16 level-3 challe…
On Oct. 28, 2022, 1:34 p.m.
The Syllabary cipher seems to be just another substitution cipher. This time, the table got mixed up. Is a solution even possible? Find it out!
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On Oct. 28, 2022, 1:32 p.m.
The Syllabary cipher seems to be just another substitution cipher, but is it? Find out and solve its mystery! All keys went missing...
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On Oct. 28, 2022, 1:30 p.m.
The Syllabary cipher seems to be just another substitution cipher, but is it? Find out and solve its mystery! But this time, the table is weird...
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On Oct. 28, 2022, 1:29 p.m.
The Syllabary cipher seems to be just another substitution cipher, but is it? Find out and solve its mystery! A key got missing...
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On Oct. 28, 2022, 1:27 p.m.
The Syllabary cipher seems to be just another substitution cipher, but is it? Find out and solve its mystery!
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On Oct. 14, 2022, 5:30 p.m.
The legendary Merkle-Hellman Knapsack cryptosystem can also be used for public-key encryption. Is the cryptosystem secure or can you crack the ciphertext?
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On Oct. 14, 2022, 5:28 p.m.
The legendary Merkle-Hellman Knapsack cryptosystem is not suitable for hiking, but it is considered a pioneer of asymmetric cryptography. Can you crack the cip…
On Sept. 4, 2022, 10:11 a.m.
The historical Hill cipher uses matrix-vector multiplications to encrypt blocks
of letters. Can you find the inverse matrix and recover the plaintext?
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On May 14, 2022, 12:22 p.m.
A more difficult and even more interesting sequel to the "Alberti Challenge - Part 1".
Will you manage to crack this puzzle this time as well?
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On March 26, 2022, 8:45 p.m.
This challenge is about one of the oldest polyalphabetic ciphers.
Can you crack this centuries-old puzzle?
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