| The Josse Challenge – Part 2 | 1,725 | Feb. 27, 2023, 9:47 a.m. |
| The Josse Challenge – Part 1 | 1,469 | Feb. 21, 2023, 8:15 a.m. |
| The Syllabary Cipher – Part 4 | 1,318 | Dec. 2, 2022, 10:42 p.m. |
| The Syllabary Cipher – Part 5 | 1,318 | Dec. 2, 2022, 7:58 p.m. |
| The Syllabary Cipher – Part 3 | 1,353 | Nov. 22, 2022, 10 p.m. |
| The Syllabary Cipher – Part 2 | 1,547 | Nov. 4, 2022, 9:38 a.m. |
| The Syllabary Cipher – Part 1 | 200 | Oct. 28, 2022, 2:44 p.m. |
| Merkle-Hellman Knapsack Challenge - Part 1 | 125 | Oct. 18, 2022, 9:19 a.m. |
| Alberti Challenge — Part 1 | 150 | March 28, 2022, 9:09 a.m. |
| Find the right route — Part 3 | 100 | Feb. 1, 2022, 12:59 p.m. |
| Modified Vigenère Cipher | 1,613 | Jan. 28, 2022, 9:04 p.m. |
| M-138 — Part 4 | 1,091 | Jan. 27, 2022, 5:31 p.m. |
| Wheatstone Cryptograph — Part 1 | 200 | April 22, 2021, 3:14 p.m. |
| Purple 1 | 1,082 | Feb. 18, 2021, 11:43 a.m. |
| Find the right route — Part 1 | 113 | Nov. 3, 2020, 8:09 p.m. |
| Polyhomophonic Substitution — Part 3 | 1,199 | Sept. 16, 2020, 8:49 a.m. |
| Polyphonic Substitution Cipher — Part 2 | 1,177 | Sept. 14, 2020, 1:19 a.m. |
| Polyphonic Substitution Cipher — Part 1 | 1,169 | Sept. 3, 2020, 11:31 a.m. |
| Lightweight Introduction to Lattices — Part 3 | 1,824 | July 17, 2020, 6:39 p.m. |
| RSA Factoring Challenge: RSA-250 | 0 | July 13, 2020, 4:19 p.m. |
| RSA Factoring Challenge: RSA-704 | 0 | July 9, 2020, 8:01 a.m. |
| RSA Factoring Challenge: RSA-240 | 0 | July 9, 2020, 7:54 a.m. |
| RSA Factoring Challenge: RSA-232 | 0 | July 9, 2020, 7:48 a.m. |
| RSA Factoring Challenge: RSA-230 | 0 | July 9, 2020, 7:44 a.m. |
| RSA Factoring Challenge: RSA-220 | 0 | July 9, 2020, 7:41 a.m. |
| RSA Factoring Challenge: RSA-210 | 0 | July 9, 2020, 7:24 a.m. |
| Number Sequence — Part 9 | 100 | June 26, 2020, 10:48 a.m. |
| Lightweight Introduction to Lattices — Part 2 | 200 | June 24, 2020, 12:58 p.m. |
| Lightweight Introduction to Lattices — Part 1 | 108 | May 28, 2020, 1:30 p.m. |
| Polyhomophonic Substitution — Part 2 | 2,000 | March 28, 2020, 11:11 p.m. |
| Polyhomophonic Substitution — Part 1 | 200 | March 22, 2020, 7:51 p.m. |
| The LoRa Cipher: Logic Randomness — Part 1 | 2,000 | Feb. 20, 2020, 8:50 a.m. |
| Sigaba Part 1 | 1,084 | Feb. 12, 2020, 6:24 p.m. |
| CMEA 2 | 13,127 | Jan. 4, 2020, 3:44 p.m. |
| Homophonic Encryption — Part 4 | 1,180 | Dec. 22, 2019, 12:16 p.m. |
| The T52 Sturgeon Challenge — Part 4 | 1,256 | Oct. 1, 2019, 6:59 p.m. |
| The T52 Sturgeon Challenge — Part 3 | 1,256 | Oct. 1, 2019, 2:41 p.m. |
| The T52 Sturgeon Challenge — Part 2 | 1,256 | Oct. 1, 2019, 11:47 a.m. |
| The T52 Sturgeon Challenge — Part 1 | 1,247 | Oct. 1, 2019, 11:45 a.m. |
| Unusual encryption using a diophantine equation | 1,088 | Sept. 21, 2019, 8:55 p.m. |
| A Cloaked Substitution Cipher — Part 1 | 1,444 | Sept. 2, 2019, 3:05 p.m. |
| A Cloaked Substitution Cipher — Part 2 | 1,523 | Sept. 2, 2019, 11:16 a.m. |
| Handycipher made in love — Part 2 | 2,000 | May 22, 2019, 11:15 a.m. |
| Homophonic Encryption — Part 2 | 1,725 | May 10, 2019, 11:47 p.m. |
| Homophonic Encryption — Part 3 | 2,000 | May 9, 2019, 10:44 a.m. |
| Homophonic Encryption — Part 1 | 1,824 | May 6, 2019, 11:43 a.m. |
| Number Sequence — Part 5 | 100 | April 3, 2019, 4:50 p.m. |
| Typex — Part 1 | 1,095 | March 5, 2019, 8:37 a.m. |
| Monoalphabetic Substitution with Nostradamus Flavor | 2,000 | Feb. 16, 2019, 11:07 p.m. |
| Handycipher made in love — Part 1 | 2,000 | Feb. 16, 2019, 10:05 p.m. |
| Cryptanalysis Hacking Puzzles — Part 2 | 200 | Jan. 10, 2019, 8 a.m. |
| Kaskade-S/T — Part 6 (RansomKaskade Part 1) | 1,142 | Dec. 2, 2018, 8 p.m. |
| Cryptanalysis Hacking Puzzles — Part 1 | 111 | Nov. 4, 2018, 11:04 a.m. |
| Breaking a Filter Generator | 1,660 | Sept. 28, 2018, 4:19 p.m. |
| Modular Sequences | 150 | Sept. 27, 2018, 12:26 p.m. |
| Autokey Cipher | 150 | Sept. 27, 2018, 11:05 a.m. |
| Typex — Part 2 | 1,098 | Aug. 23, 2018, 12:17 p.m. |
| Ku Klux Klan | 1,000 | Aug. 13, 2018, 2:59 p.m. |
| Hilly — Part 1 | 1,141 | July 14, 2018, 9:53 a.m. |
| Trendy Messenger | 1,547 | June 19, 2018, 7:44 a.m. |
| Summer Job | 1,824 | June 13, 2018, 3:53 p.m. |
| Fastest in the West | 2,000 | June 13, 2018, 10:36 a.m. |
| An Invisible Message | 100 | June 9, 2018, 9:14 a.m. |
| Number Sequence — Part 10 | 102 | June 7, 2018, 4:49 p.m. |
| Monoalphabetic Substitution with Camouflage — Part 5 | 1,095 | March 13, 2018, 2:44 p.m. |
| Monoalphabetic substitution with camouflage — Part 3 | 1,094 | March 12, 2018, 7:42 p.m. |
| Monoalphabetic substitution with camouflage — Part 2 | 1,094 | March 12, 2018, 10:58 a.m. |
| The Einstein Enigma | 1,824 | Feb. 9, 2018, 7:29 a.m. |
| An 'unhearable' message | 100 | Feb. 8, 2018, 7:53 p.m. |
| Advent Challenge — Part 3 | 2,000 | Dec. 22, 2017, 7:34 p.m. |
| Advent Challenge — Part 4 | 2,000 | Dec. 22, 2017, 8:16 a.m. |
| Advent-Challenge — Part 2 | 2,000 | Dec. 17, 2017, 11:20 a.m. |
| Advent-Challenge — Part 1 | 150 | Dec. 10, 2017, 9:25 a.m. |
| Monoalphabetic substitution with camouflage — Part 1 | 100 | Dec. 8, 2017, 5:53 p.m. |
| New Year's Greetings — Part 4 | 100 | Nov. 8, 2017, 8:15 a.m. |
| New Year's Greetings — Part 3 | 100 | Nov. 8, 2017, 7:56 a.m. |
| New Year's Greetings — Part 2 | 100 | Nov. 8, 2017, 7:48 a.m. |
| New Year's Greetings — Part 1 | 100 | Nov. 8, 2017, 7:35 a.m. |
| Image Noise | 100 | June 14, 2017, 10:26 a.m. |
| Turing Bombe Enigma I | 100 | June 9, 2017, 4:42 p.m. |
| Kaskade-S/T — Part 3 | 1,094 | June 1, 2017, 3:56 p.m. |
| Spanish Strip Cipher — Part 2 | 1,114 | May 17, 2017, 10:36 a.m. |
| CMEA 1 | 1,095 | Dec. 11, 2016, 10:37 a.m. |
| ASAC — A Strong(er) ADFGVX Cipher — Part 1 | 1,204 | Dec. 6, 2016, 4:18 p.m. |
| Monoalphabetic substitution with camouflage — Part 4 | 100 | Nov. 22, 2016, 8:25 p.m. |
| Post-Quantum Cryptography: Unbalanced Oil and Vinegar System — Part 1 | 100 | Nov. 17, 2016, 8:22 p.m. |
| Strange Message from Thessaloniki | 100 | Nov. 17, 2016, 11:39 a.m. |
| Music Code — Part 1 | 100 | Nov. 16, 2016, 3:45 p.m. |
| Music Code — Part 2 | 1,097 | Nov. 16, 2016, 3:32 p.m. |
| Number Sequence — Part 7 | 100 | Nov. 9, 2016, 12:19 p.m. |
| Kaskade-S/T — Part 2 | 1,097 | Nov. 7, 2016, 10:11 a.m. |
| Molehunt (Part 3/3) | 1,095 | Nov. 5, 2016, 9:47 a.m. |
| Zodiac Cipher | 100 | Nov. 5, 2016, 9:07 a.m. |
| Snow White and the seven dwarfs | 100 | Oct. 24, 2016, 5:59 p.m. |
| Heartbleed — Part 1 | 100 | Oct. 22, 2016, 10:23 a.m. |
| Weakened Granit — Part 1 | 100 | Oct. 19, 2016, 7:46 a.m. |
| Double Column Transposition — Part 1 | 1,121 | Oct. 17, 2016, 2:47 p.m. |
| Double Column Transposition — Part 2 | 1,122 | Oct. 17, 2016, 2:35 p.m. |
| Double Column Transposition — Part 3 | 1,122 | Oct. 17, 2016, 12:45 p.m. |
| M-138 — Part 3 | 1,133 | Oct. 16, 2016, 7:29 a.m. |
| Flawed Usage of a OTP Cipher by the BND | 1,152 | Oct. 10, 2016, 6:28 p.m. |
| Brute-Force-Attack on Triple-DES with Reduced Key Space | 1,095 | Oct. 8, 2016, 1:14 p.m. |
| A hidden word — Part 2 | 100 | Sept. 30, 2016, 6:28 p.m. |
| Nils away on travel | 100 | Sept. 30, 2016, 6:07 p.m. |
| Recycled One-Time Pad | 100 | Sept. 27, 2016, 12:02 p.m. |
| Molehunt (Part 1/3) | 100 | March 21, 2016, 9:39 a.m. |
| Letter from the Alleged Countess Julie von Ortenburg | 100 | March 16, 2016, 6:30 p.m. |
| Unconcealed RSA messages | 1,104 | March 11, 2016, 6:27 p.m. |
| Hill Cipher with Sudoku Key | 100 | March 8, 2016, 11:48 a.m. |
| Keyshanc — Part 2 | 1,108 | March 4, 2016, 5:46 p.m. |
| Keyshanc — Part 1 | 1,108 | March 3, 2016, 10:40 a.m. |
| The Last Note | 100 | Feb. 29, 2016, 7:46 p.m. |
| Cascading Encryption — Part 1/3 | 100 | Feb. 22, 2016, 3:21 p.m. |
| How do you become a big cryptographer? | 100 | Feb. 5, 2016, 7:26 p.m. |
| News from Castle Mansfeld | 101 | Feb. 5, 2016, 7:06 p.m. |
| A Secret Message from Castle Mansfeld | 100 | Feb. 5, 2016, 5:33 p.m. |
| Lunchtime Attack on the Fully Homomorphic Encryption Scheme | 1,100 | Jan. 29, 2016, 2:41 p.m. |
| Enigma Messages with Repeated Letters — Part 5 | 100 | Jan. 16, 2016, 4:38 p.m. |
| Enigma Messages with Repeated Letters — Part 4 | 100 | Jan. 16, 2016, 4:34 p.m. |
| Enigma Messages with Repeated Letters — Part 2 | 100 | Jan. 15, 2016, 5:59 p.m. |
| Enigma Messages with Repeated Letters — Part 3 | 100 | Jan. 12, 2016, 7:51 p.m. |
| Double Column Transposition — Part 4 | 1,136 | Jan. 12, 2016, 7:07 p.m. |
| Enigma Messages | 100 | Jan. 12, 2016, 12:25 p.m. |
| Enigma Part 1 | 1,099 | Jan. 12, 2016, 11:30 a.m. |
| Enigma Part 2 | 1,099 | Jan. 12, 2016, 11:01 a.m. |
| Enigma Messages with Repeated Letters — Part 1 | 100 | Jan. 9, 2016, 2:24 p.m. |
| ORYX Stream Cipher — Part 3 (revised) | 1,121 | Dec. 17, 2015, 7:31 p.m. |
| ORYX Stream Cipher Part II | 1,099 | Dec. 13, 2015, 10:14 a.m. |
| ORYX Stream Cipher Part I | 1,099 | Dec. 11, 2015, 12:53 p.m. |
| Hybrid Encryption I | 1,100 | Nov. 23, 2015, 2:03 p.m. |
| Pigpen with a twist — Part 2 | 1,105 | Nov. 19, 2015, 6:50 p.m. |
| Partial Key Exposure with RSA — Part 1 | 1,108 | Nov. 18, 2015, 10 a.m. |
| Pigpen with a twist — Part 3 | 1,105 | Nov. 17, 2015, 2:36 p.m. |
| Monoalphabetic Substitution | 100 | Nov. 15, 2015, 7:58 a.m. |
| Playfair with hints about the grid | 100 | Nov. 13, 2015, 7:47 a.m. |
| Playfair Encryption | 100 | Nov. 13, 2015, 7:37 a.m. |
| AES key — encoded in the machine readable zone of a European ePassport | 1,108 | Nov. 9, 2015, 3:48 p.m. |
| Molehunt (Part 2/3) | 100 | Nov. 6, 2015, 4:55 p.m. |
| Factorization Cipher — Part 2 | 1,107 | Nov. 6, 2015, 9:16 a.m. |
| Factorization Cipher — Part 3 | 1,108 | Nov. 6, 2015, 8:33 a.m. |
| Double Columnar Transposition | 100 | Nov. 3, 2015, 9:25 a.m. |
| ECDH-Key Exchange for Beginners | 100 | Nov. 3, 2015, 6:03 a.m. |
| M-138 — Part 2 | 1,164 | Nov. 2, 2015, 7:42 a.m. |
| RSA: Two different keys — same ciphertext | 1,105 | Oct. 30, 2015, 5:47 p.m. |
| Broadcasting and low exponent — RSA Attack | 1,104 | Oct. 30, 2015, 5:18 p.m. |
| Not-so-Secret Message from Malawi — Part I (RSA) | 1,100 | Oct. 30, 2015, 4:40 p.m. |
| BCR code (Book-Caesar-RSA) | 1,114 | Oct. 30, 2015, 3:35 p.m. |
| Spanish Strip Cipher — Part 1 | 1,139 | Oct. 14, 2015, 7:49 p.m. |
| Classical Ciphers^3 | 100 | Oct. 12, 2015, 9:07 a.m. |
| ADFGVX — Part 1 | 100 | Oct. 11, 2015, 2:17 p.m. |
| ADFGVX — Part 2 | 100 | Oct. 11, 2015, 1:35 p.m. |
| Alice's Birthday Party (Part 1) | 1,100 | Oct. 8, 2015, 12:24 p.m. |
| Alice's Birthday Party (Part 2) | 1,100 | Oct. 8, 2015, 11:07 a.m. |
| A modified homophonic cipher with reduced alphabets — Part 1 | 100 | Oct. 7, 2015, 6:29 p.m. |
| A modified homophonic cipher with reduced alphabets — Part 2 | 100 | Oct. 7, 2015, 6:21 p.m. |
| Trifid Cipher | 100 | Oct. 7, 2015, 11:50 a.m. |
| Pigpen with a twist — Part 1 | 100 | Oct. 7, 2015, 7:13 a.m. |
| Kaskade-S/T — Part 1 | 100 | Oct. 6, 2015, 7:31 p.m. |
| Beaver Code | 100 | Oct. 5, 2015, 2:04 p.m. |
| A hidden word | 100 | Oct. 3, 2015, 5:46 a.m. |
| Multilingual Monoalphabetic Substitution | 100 | Oct. 2, 2015, 4:06 p.m. |
| Number Sequence — Part 8 | 105 | Oct. 2, 2015, 2:23 p.m. |
| Number Sequence — Part 6 | 101 | Oct. 2, 2015, 2:17 p.m. |
| From Russia with Love | 100 | Oct. 1, 2015, 4:13 p.m. |
| The Book Code: A Challenge for Bookworms | 100 | Oct. 1, 2015, 3:37 p.m. |
| One-Time Pad with Flaws | 100 | Oct. 1, 2015, 6:04 a.m. |
| M-138 — Part 1 | 100 | Sept. 30, 2015, 10:13 a.m. |
| Reserve Hand Procedure — Part 1 | 100 | Sept. 30, 2015, 8 a.m. |
| ¿No Hablas Español? No problemo! | 100 | Sept. 30, 2015, 5:48 a.m. |
| Grille Cipher | 100 | Sept. 29, 2015, 3:06 p.m. |
| Cracking SHA1-Hashed Passwords | 1,103 | Sept. 29, 2015, 2:03 p.m. |
| Letter to the Templars — Part 3 | 1,116 | Sept. 29, 2015, 9:40 a.m. |
| Modified Caesar Cipher | 100 | Sept. 29, 2015, 9:25 a.m. |
| Factorization Cipher — Part 1 | 100 | Sept. 28, 2015, 4:36 p.m. |
| Affine Codes / Modulo Arithmetic with N / Extended Euclid | 100 | Sept. 28, 2015, 4:20 p.m. |
| Number Sequence — Part 4 | 100 | Sept. 28, 2015, 3:49 p.m. |
| Letter to the Templars — Part 2 | 100 | Sept. 28, 2015, 3:42 p.m. |
| Caesar Encryption | 100 | Sept. 28, 2015, 3:31 p.m. |
| Number Sequence — Part 2 | 100 | Sept. 28, 2015, 3:12 p.m. |
| Number Sequence — Part 3 | 100 | Sept. 28, 2015, 3:07 p.m. |
| Letter to the Templars — Part 1 | 100 | Sept. 28, 2015, 3:03 p.m. |
| Original Caesar Cipher | 100 | Sept. 28, 2015, 2:49 p.m. |
| Number Sequence | 100 | Sept. 28, 2015, 2:44 p.m. |
Gold1
Silver1
Bronze6
