| The Hutton Cipher – Part 1 | 2,000 | May 3, 2023, 11:31 a.m. |
| Wheatstone Cryptograph — Part 2 | 1,131 | April 11, 2023, 2:40 a.m. |
| Fastest in the West | 1,101 | March 30, 2023, 12:29 p.m. |
| The Josse Challenge – Part 3 | 2,000 | March 27, 2023, 11:33 a.m. |
| The Josse Challenge – Part 2 | 2,000 | Feb. 25, 2023, 1:50 a.m. |
| Pigpen with a twist — Part 3 | 1,080 | Feb. 21, 2023, 4:32 a.m. |
| The Josse Challenge – Part 1 | 1,469 | Feb. 20, 2023, 5:57 p.m. |
| Pigpen with a twist — Part 2 | 1,080 | Feb. 18, 2023, 5:07 a.m. |
| The LoRa Cipher: Logic Randomness — Part 1 | 1,116 | Feb. 6, 2023, 3:16 a.m. |
| The SIGABA Challenge — Part 2 | 1,116 | Feb. 4, 2023, 3:12 a.m. |
| Sigaba Part 1 | 1,078 | Jan. 22, 2023, 1:15 p.m. |
| The SIGABA Challenge — Part 1 | 1,116 | Jan. 19, 2023, 1:39 a.m. |
| The Syllabary Cipher – Part 5 | 1,333 | Nov. 28, 2022, 3:37 a.m. |
| The Syllabary Cipher – Part 4 | 1,398 | Nov. 14, 2022, 2:40 p.m. |
| The Syllabary Cipher – Part 3 | 1,456 | Nov. 8, 2022, 11:17 p.m. |
| The Syllabary Cipher – Part 2 | 1,613 | Nov. 1, 2022, 3:58 p.m. |
| The Syllabary Cipher – Part 1 | 120 | Nov. 1, 2022, 12:30 p.m. |
| Purple 1 | 1,079 | Nov. 1, 2022, 4:34 a.m. |
| Merkle-Hellman Knapsack Challenge — Part 2 | 1,456 | Oct. 26, 2022, 12:17 p.m. |
| Merkle-Hellman Knapsack Challenge - Part 1 | 117 | Oct. 20, 2022, 9:35 a.m. |
| Hill Cipher | 1,406 | Sept. 20, 2022, 10:24 p.m. |
| Alberti Challenge — Part 2 | 1,266 | July 16, 2022, 12:16 a.m. |
| Alberti Challenge — Part 1 | 101 | July 9, 2022, 3:32 a.m. |
| Advent Challenge — Part 4 | 1,105 | Feb. 24, 2022, 3:39 p.m. |
| Advent Challenge — Part 3 | 1,105 | Feb. 24, 2022, 12:56 a.m. |
| Double Column Transposition — Part 4 | 1,089 | Feb. 23, 2022, 2:40 p.m. |
| Double Column Transposition — Part 3 | 1,089 | Feb. 21, 2022, 4:01 p.m. |
| Double Column Transposition — Part 2 | 1,089 | Feb. 21, 2022, 11:16 a.m. |
| Double Column Transposition — Part 1 | 1,088 | Feb. 18, 2022, 6:42 p.m. |
| "The Road" — Part 1 | 1,113 | Feb. 17, 2022, 2:11 a.m. |
| Keyshanc — Part 2 | 1,083 | Feb. 14, 2022, 7:40 p.m. |
| Keyshanc — Part 1 | 1,083 | Feb. 13, 2022, 11:53 p.m. |
| Lunchtime Attack on the Fully Homomorphic Encryption Scheme | 1,081 | Feb. 13, 2022, 1:40 a.m. |
| Summer Job | 1,109 | Feb. 12, 2022, 12:36 a.m. |
| Modified Vigenère Cipher | 1,406 | Feb. 9, 2022, 12:57 p.m. |
| Kaskade-S/T — Part 3 | 1,081 | Oct. 30, 2021, 6:33 p.m. |
| Kaskade-S/T — Part 2 | 1,081 | Oct. 23, 2021, 11:06 p.m. |
| Wheatstone Cryptograph — Part 1 | 117 | April 27, 2021, 3:08 a.m. |
| M-138 — Part 4 | 1,094 | April 26, 2021, 3:51 p.m. |
| The Einstein Enigma | 1,113 | April 18, 2021, 1:39 p.m. |
| M-138 — Part 3 | 1,094 | April 17, 2021, 2:26 p.m. |
| Unusual encryption using a diophantine equation | 1,084 | April 16, 2021, 12:18 a.m. |
| AES key — encoded in the machine readable zone of a European ePassport | 1,085 | Dec. 31, 2020, 5:08 p.m. |
| Find the right route — Part 3 | 125 | Dec. 30, 2020, 2:32 a.m. |
| Find the right route — Part 2 | 110 | Dec. 29, 2020, 1:11 a.m. |
| Smartcard RSA | 1,082 | Dec. 27, 2020, 2:33 a.m. |
| Lightweight Introduction to Lattices — Part 3 | 1,201 | Dec. 21, 2020, 3:51 a.m. |
| Lightweight Introduction to Lattices — Part 2 | 101 | Dec. 18, 2020, 11:24 p.m. |
| Polyhomophonic Substitution — Part 3 | 1,174 | Dec. 18, 2020, 2:33 a.m. |
| Polyhomophonic Substitution — Part 2 | 1,173 | Dec. 14, 2020, 1:48 p.m. |
| Polyphonic Substitution Cipher — Part 2 | 1,161 | Dec. 12, 2020, 11:30 p.m. |
| Polyphonic Substitution Cipher — Part 1 | 1,155 | Dec. 11, 2020, 3:27 p.m. |
| Advent-Challenge — Part 2 | 1,116 | Dec. 6, 2020, 12:28 a.m. |
| Find the right route — Part 1 | 103 | Dec. 5, 2020, 12:25 a.m. |
| Homophonic Encryption — Part 4 | 1,138 | Dec. 4, 2020, 5:55 p.m. |
| Homophonic Encryption — Part 3 | 1,138 | Dec. 4, 2020, 5:34 p.m. |
| Homophonic Encryption — Part 2 | 1,138 | Dec. 4, 2020, 2:17 a.m. |
| Homophonic Encryption — Part 1 | 1,138 | Dec. 2, 2020, 8:22 p.m. |
| Lightweight Introduction to Lattices — Part 1 | 101 | Dec. 2, 2020, 12:24 a.m. |
| Polyhomophonic Substitution — Part 1 | 100 | Nov. 29, 2020, 1:19 a.m. |
| Unconcealed RSA messages | 1,089 | July 11, 2019, 2:20 p.m. |
| BCR code (Book-Caesar-RSA) | 1,092 | July 7, 2019, 4:53 p.m. |
| Monoalphabetic Substitution with Nostradamus Flavor | 1,217 | June 18, 2019, 5:17 p.m. |
| Partial Key Exposure with RSA — Part 1 | 1,090 | June 18, 2019, 11:44 a.m. |
| Molehunt (Part 3/3) | 1,087 | March 15, 2019, 10:02 a.m. |
| Cryptanalysis Hacking Puzzles — Part 2 | 102 | March 14, 2019, 3:40 p.m. |
| Factorization Cipher — Part 3 | 1,091 | March 14, 2019, 8:32 a.m. |
| ORYX Stream Cipher — Part 4a | 1,101 | March 11, 2019, 11:55 p.m. |
| ORYX Stream Cipher — Part 3 (revised) | 1,096 | Feb. 18, 2019, 1:22 p.m. |
| ORYX Stream Cipher Part II | 1,087 | Feb. 15, 2019, 6:09 p.m. |
| ORYX Stream Cipher Part I | 1,087 | Feb. 14, 2019, 12:35 p.m. |
| A really long number sequence | 1,090 | Feb. 4, 2019, 5:44 p.m. |
| Monoalphabetic substitution with camouflage — Part 4 | 100 | Feb. 3, 2019, 1:36 p.m. |
| New Year's Greetings — Part 5 | 1,117 | Feb. 2, 2019, 9:30 a.m. |
| M-138 — Part 2 | 1,106 | Jan. 30, 2019, 1:17 a.m. |
| Hybrid Encryption I | 1,087 | Jan. 29, 2019, 2:46 a.m. |
| Enigma Part 1 | 1,087 | Jan. 26, 2019, 6:04 p.m. |
| Enigma Part 2 | 1,087 | Jan. 25, 2019, 8:53 p.m. |
| Brute-Force-Attack on Triple-DES with Reduced Key Space | 1,087 | Jan. 25, 2019, 12:13 a.m. |
| Multilingual Monoalphabetic Substitution | 100 | Jan. 22, 2019, 3:34 p.m. |
| Monoalphabetic substitution with camouflage — Part 3 | 1,091 | Jan. 18, 2019, 11:56 a.m. |
| Monoalphabetic substitution with camouflage — Part 2 | 1,091 | Jan. 17, 2019, 8:27 a.m. |
| Weakened Granit — Part 1 | 100 | Jan. 15, 2019, 3:33 p.m. |
| Autokey Cipher | 101 | Jan. 15, 2019, 1:34 a.m. |
| Heartbleed — Part 2 | 100 | Jan. 14, 2019, 7:25 p.m. |
| A hidden word — Part 2 | 100 | Jan. 13, 2019, 10:58 p.m. |
| Modular Sequences | 101 | Jan. 13, 2019, 12:05 p.m. |
| Number Sequence — Part 10 | 100 | Jan. 12, 2019, 2:36 a.m. |
| Number Sequence — Part 7 | 100 | Jan. 11, 2019, 9:19 p.m. |
| Number Sequence — Part 9 | 100 | Jan. 11, 2019, 8:48 p.m. |
| New Year's Greetings — Part 4 | 100 | Jan. 11, 2019, 6:38 p.m. |
| New Year's Greetings — Part 3 | 100 | Jan. 11, 2019, 1:24 a.m. |
| Enigma Messages with Repeated Letters — Part 5 | 100 | Jan. 10, 2019, 11:03 a.m. |
| Enigma Messages with Repeated Letters — Part 4 | 100 | Jan. 10, 2019, 2:35 a.m. |
| New Year's Greetings — Part 2 | 100 | Jan. 7, 2019, 11:06 p.m. |
| Advent-Challenge — Part 1 | 100 | Jan. 6, 2019, 12:42 a.m. |
| News from Castle Mansfeld | 100 | Jan. 5, 2019, 11:26 a.m. |
| Enigma Messages with Repeated Letters — Part 3 | 100 | Jan. 2, 2019, 12:06 a.m. |
| Enigma Messages with Repeated Letters — Part 2 | 100 | Dec. 31, 2018, 11:34 a.m. |
| Hill Cipher with Sudoku Key | 100 | Dec. 29, 2018, 10:11 p.m. |
| Cryptanalysis Hacking Puzzles — Part 1 | 102 | Dec. 27, 2018, 7:40 p.m. |
| Strange Message from Thessaloniki | 100 | Dec. 19, 2018, 12:14 a.m. |
| Recycled One-Time Pad | 100 | Dec. 18, 2018, 6:33 p.m. |
| An 'unhearable' message | 100 | Dec. 14, 2018, 9:29 p.m. |
| Enigma Messages | 100 | Dec. 10, 2018, 1:39 p.m. |
| Number Sequence — Part 5 | 100 | Dec. 6, 2018, 9:43 a.m. |
| Monoalphabetic substitution with camouflage — Part 1 | 100 | Dec. 4, 2018, 11:13 p.m. |
| Turing Bombe Enigma I | 100 | Dec. 3, 2018, 6:59 p.m. |
| An Invisible Message | 100 | Nov. 24, 2018, 2:10 a.m. |
| Music Code — Part 2 | 1,089 | Nov. 23, 2018, 10:24 a.m. |
| Music Code — Part 1 | 100 | Nov. 22, 2018, 11:16 p.m. |
| Zodiac Cipher | 100 | Aug. 20, 2018, 12:43 a.m. |
| Heartbleed — Part 1 | 100 | Feb. 15, 2017, 10:27 a.m. |
| Factorization Cipher — Part 2 | 1,099 | Feb. 12, 2017, 9:07 a.m. |
| Post-Quantum Cryptography: Unbalanced Oil and Vinegar System — Part 1 | 100 | Feb. 2, 2017, 9:42 a.m. |
| RSA: Two different keys — same ciphertext | 1,098 | Jan. 29, 2017, 10:55 p.m. |
| Cascading Encryption — Part 1/3 | 100 | Jan. 29, 2017, 12:59 a.m. |
| Not-so-Secret Message from Malawi — Part I (RSA) | 1,094 | Jan. 26, 2017, 8:39 a.m. |
| Broadcasting and low exponent — RSA Attack | 1,097 | Jan. 25, 2017, 9:15 a.m. |
| Alice's Birthday Party (Part 2) | 1,094 | Jan. 25, 2017, 2:09 a.m. |
| The Last Note | 100 | Jan. 24, 2017, 11:40 p.m. |
| Number Sequence — Part 6 | 100 | Jan. 24, 2017, 1:40 p.m. |
| Playfair with hints about the grid | 100 | Jan. 24, 2017, 12:44 p.m. |
| Alice's Birthday Party (Part 1) | 1,094 | Jan. 24, 2017, 12:41 p.m. |
| Double Columnar Transposition | 100 | Jan. 17, 2017, 8:19 a.m. |
| ECDH-Key Exchange for Beginners | 100 | Jan. 13, 2017, 2:36 p.m. |
| Playfair Encryption | 100 | Dec. 31, 2016, 12:17 a.m. |
| ADFGVX — Part 1 | 100 | Dec. 29, 2016, 2:59 a.m. |
| Kaskade-S/T — Part 1 | 100 | Dec. 29, 2016, 12:33 a.m. |
| Enigma Combinatorics | 100 | Dec. 28, 2016, 1:58 a.m. |
| ADFGVX — Part 2 | 100 | Dec. 21, 2016, 12:52 a.m. |
| ¿No Hablas Español? No problemo! | 100 | Dec. 19, 2016, 10:44 a.m. |
| Molehunt (Part 2/3) | 100 | Dec. 19, 2016, 9:56 a.m. |
| Nils away on travel | 100 | Dec. 19, 2016, 12:45 a.m. |
| Pigpen with a twist — Part 1 | 100 | Dec. 18, 2016, 3:25 a.m. |
| M-138 — Part 1 | 100 | Dec. 18, 2016, 1:04 a.m. |
| Enigma Messages with Repeated Letters — Part 1 | 100 | Dec. 17, 2016, 2:41 a.m. |
| Reserve Hand Procedure — Part 1 | 100 | Dec. 17, 2016, 1:52 a.m. |
| Modified Caesar Cipher | 100 | Dec. 16, 2016, 4:12 p.m. |
| Letter from the Alleged Countess Julie von Ortenburg | 100 | Dec. 14, 2016, 1:38 a.m. |
| Image Noise | 100 | Dec. 12, 2016, 9:52 a.m. |
| Number Sequence — Part 8 | 100 | Dec. 12, 2016, 1:14 a.m. |
| One-Time Pad with Flaws | 100 | Dec. 12, 2016, 12:31 a.m. |
| A modified homophonic cipher with reduced alphabets — Part 2 | 100 | Dec. 11, 2016, 1:40 a.m. |
| Cracking SHA1-Hashed Passwords | 1,097 | Dec. 11, 2016, 1:20 a.m. |
| A modified homophonic cipher with reduced alphabets — Part 1 | 100 | Dec. 9, 2016, 12:13 p.m. |
| Letter to the Templars — Part 3 | 1,105 | Dec. 9, 2016, 2:21 a.m. |
| Letter to the Templars — Part 2 | 100 | Dec. 8, 2016, 2:08 p.m. |
| Number Sequence — Part 4 | 100 | Dec. 7, 2016, 1:22 a.m. |
| Factorization Cipher — Part 1 | 100 | Dec. 7, 2016, 12:49 a.m. |
| Affine Codes / Modulo Arithmetic with N / Extended Euclid | 100 | Dec. 7, 2016, 12:08 a.m. |
| How do you become a big cryptographer? | 100 | Dec. 5, 2016, 2:05 a.m. |
| Snow White and the seven dwarfs | 100 | Dec. 3, 2016, 9:20 a.m. |
| Grille Cipher | 100 | Dec. 2, 2016, 9:09 a.m. |
| A hidden word | 100 | Dec. 1, 2016, 10 p.m. |
| New Year's Greetings — Part 1 | 100 | Dec. 1, 2016, 12:02 p.m. |
| Letter to the Templars — Part 1 | 100 | Nov. 30, 2016, 11:39 p.m. |
| Number Sequence — Part 3 | 100 | Nov. 30, 2016, 11:37 p.m. |
| The Book Code: A Challenge for Bookworms | 100 | Nov. 30, 2016, 6:15 p.m. |
| Beaver Code | 100 | Nov. 30, 2016, 6:11 p.m. |
| Trifid Cipher | 100 | Nov. 29, 2016, 11:48 p.m. |
| From Russia with Love | 100 | Nov. 29, 2016, 12:32 a.m. |
| A Secret Message from Castle Mansfeld | 100 | Nov. 27, 2016, 11:33 p.m. |
| Number Sequence — Part 2 | 100 | Nov. 27, 2016, 11:57 a.m. |
| Classical Ciphers^3 | 100 | Nov. 27, 2016, 11:35 a.m. |
| Caesar Encryption | 100 | Nov. 24, 2016, 12:12 p.m. |
| Molehunt (Part 1/3) | 100 | Nov. 24, 2016, 10:22 a.m. |
| Original Caesar Cipher | 100 | Nov. 17, 2016, 10:28 a.m. |
| Monoalphabetic Substitution | 100 | Nov. 16, 2016, 10:07 p.m. |
| Number Sequence | 100 | Nov. 16, 2016, 5:40 p.m. |
Gold2
Silver1
Bronze0
