| Merkle-Hellman Knapsack Challenge - Part 1 | 103 | Nov. 13, 2022, 4:40 a.m. |
| The Syllabary Cipher – Part 1 | 106 | Nov. 12, 2022, 12:56 p.m. |
| Lightweight Introduction to Lattices — Part 3 | 1,125 | Oct. 22, 2022, 9:55 a.m. |
| Lightweight Introduction to Lattices — Part 2 | 100 | Sept. 25, 2022, 7:02 p.m. |
| Lightweight Introduction to Lattices — Part 1 | 100 | Sept. 25, 2022, 2:29 p.m. |
| Alberti Challenge — Part 1 | 101 | July 13, 2022, 2:32 a.m. |
| Zodiac Cipher | 100 | July 12, 2022, 10:56 a.m. |
| Wheatstone Cryptograph — Part 1 | 100 | Feb. 5, 2022, 10:49 a.m. |
| Number Sequence — Part 5 | 100 | May 24, 2021, 2:31 p.m. |
| Polyhomophonic Substitution — Part 2 | 1,152 | May 15, 2021, 5:14 p.m. |
| Polyhomophonic Substitution — Part 1 | 100 | May 13, 2021, 6:05 p.m. |
| Homophonic Encryption — Part 4 | 1,129 | May 13, 2021, 4:47 p.m. |
| Homophonic Encryption — Part 3 | 1,129 | May 13, 2021, 4:36 p.m. |
| Homophonic Encryption — Part 2 | 1,129 | May 13, 2021, 3:22 p.m. |
| M-138 — Part 4 | 1,094 | March 15, 2021, 3:31 p.m. |
| Monoalphabetic substitution with camouflage — Part 1 | 100 | Nov. 21, 2020, 2:39 p.m. |
| Polyphonic Substitution Cipher — Part 2 | 1,165 | Nov. 18, 2020, 4:11 p.m. |
| Polyphonic Substitution Cipher — Part 1 | 1,164 | Oct. 3, 2020, 9:21 a.m. |
| Homophonic Encryption — Part 1 | 1,156 | May 17, 2020, 12:33 p.m. |
| Molehunt (Part 3/3) | 1,084 | March 19, 2020, 2:46 a.m. |
| Molehunt (Part 2/3) | 100 | March 17, 2020, 6:04 p.m. |
| Molehunt (Part 1/3) | 100 | March 17, 2020, 4:44 p.m. |
| Autokey Cipher | 100 | Dec. 22, 2019, 8:09 p.m. |
| Number Sequence — Part 10 | 100 | Dec. 20, 2019, 5:38 p.m. |
| Modular Sequences | 100 | Dec. 20, 2019, 5:11 p.m. |
| Number Sequence — Part 9 | 102 | Jan. 6, 2018, 3:01 p.m. |
| Advent Challenge — Part 3 | 1,423 | Jan. 6, 2018, 11:17 a.m. |
| Advent-Challenge — Part 2 | 1,613 | Dec. 21, 2017, 4:34 p.m. |
| Advent-Challenge — Part 1 | 108 | Dec. 20, 2017, 10:10 a.m. |
| Enigma Part 1 | 1,091 | Oct. 29, 2017, 2:50 p.m. |
| Enigma Messages | 100 | Oct. 29, 2017, 9:22 a.m. |
| Enigma Combinatorics | 100 | Oct. 23, 2017, 8:44 a.m. |
| Hill Cipher with Sudoku Key | 100 | Oct. 12, 2017, 4:42 p.m. |
| Number Sequence — Part 6 | 100 | Jan. 11, 2017, 2:11 p.m. |
| Number Sequence — Part 3 | 100 | Jan. 11, 2017, 12:27 p.m. |
| Unusual encryption using a diophantine equation | 1,098 | Jan. 2, 2017, 4:13 p.m. |
| Number Sequence — Part 7 | 100 | Jan. 1, 2017, 5:20 p.m. |
| Number Sequence — Part 8 | 100 | Dec. 26, 2016, 4:27 p.m. |
| New Year's Greetings — Part 4 | 100 | Nov. 17, 2016, 4:14 a.m. |
| New Year's Greetings — Part 3 | 100 | Nov. 16, 2016, 4:20 p.m. |
| Brute-Force-Attack on Triple-DES with Reduced Key Space | 1,095 | Nov. 13, 2016, 4:49 p.m. |
| Double Columnar Transposition | 100 | Nov. 13, 2016, 10:41 a.m. |
| Strange Message from Thessaloniki | 100 | Nov. 1, 2016, 12:07 p.m. |
| New Year's Greetings — Part 2 | 102 | May 15, 2016, 6:53 p.m. |
| Ku Klux Klan | 1,000 | May 15, 2016, 3:40 p.m. |
| Reserve Hand Procedure — Part 1 | 100 | April 30, 2016, 12:27 p.m. |
| Spanish Strip Cipher — Part 2 | 1,128 | April 18, 2016, 9:11 a.m. |
| M-138 — Part 3 | 1,146 | April 12, 2016, 11:43 p.m. |
| New Year's Greetings — Part 1 | 105 | April 9, 2016, 9:56 a.m. |
| Not-so-Secret Message from Malawi — Part II (ECC) | 1,098 | March 22, 2016, 12:29 p.m. |
| Factorization Cipher — Part 3 | 1,106 | Jan. 15, 2016, 7:48 p.m. |
| ECDH-Key Exchange for Beginners | 100 | Jan. 2, 2016, 11:18 a.m. |
| Number Sequence — Part 4 | 100 | Dec. 21, 2015, 9:06 p.m. |
| Letter from the Alleged Countess Julie von Ortenburg | 100 | Dec. 19, 2015, 12:13 p.m. |
| A hidden word — Part 2 | 100 | Dec. 17, 2015, 6:28 a.m. |
| Enigma Messages with Repeated Letters — Part 3 | 100 | Dec. 13, 2015, 10:15 a.m. |
| ADFGVX — Part 2 | 100 | Dec. 5, 2015, 10:32 a.m. |
| ADFGVX — Part 1 | 100 | Nov. 29, 2015, 2:40 p.m. |
| The Last Note | 100 | Nov. 29, 2015, 7:38 a.m. |
| Spanish Strip Cipher — Part 1 | 1,136 | Nov. 26, 2015, 7:53 p.m. |
| News from Castle Mansfeld | 113 | Nov. 21, 2015, 11:15 a.m. |
| Not-so-Secret Message from Malawi — Part I (RSA) | 1,100 | Nov. 14, 2015, 1:12 p.m. |
| RSA: Two different keys — same ciphertext | 1,105 | Nov. 10, 2015, 11:27 a.m. |
| Broadcasting and low exponent — RSA Attack | 1,104 | Nov. 9, 2015, 4:25 p.m. |
| Alice's Birthday Party (Part 2) | 1,100 | Nov. 9, 2015, 3:27 p.m. |
| Alice's Birthday Party (Part 1) | 1,100 | Nov. 8, 2015, 3:30 p.m. |
| From Russia with Love | 100 | Nov. 8, 2015, 8:01 a.m. |
| Cracking SHA1-Hashed Passwords | 1,102 | Nov. 6, 2015, 1:24 p.m. |
| A Secret Message from Castle Mansfeld | 100 | Nov. 3, 2015, 3:34 a.m. |
| Factorization Cipher — Part 2 | 1,107 | Oct. 29, 2015, 3:51 p.m. |
| Factorization Cipher — Part 1 | 100 | Oct. 27, 2015, 6:04 a.m. |
| M-138 — Part 2 | 1,166 | Oct. 25, 2015, 3:31 a.m. |
| Grille Cipher | 100 | Oct. 24, 2015, 8:10 p.m. |
| M-138 — Part 1 | 100 | Oct. 24, 2015, 4:29 p.m. |
| Affine Codes / Modulo Arithmetic with N / Extended Euclid | 100 | Oct. 24, 2015, 3:15 p.m. |
| Modified Caesar Cipher | 100 | Oct. 24, 2015, 2:55 p.m. |
| Monoalphabetic Substitution | 100 | Oct. 24, 2015, 2:47 p.m. |
| A hidden word | 100 | Oct. 18, 2015, 12:33 p.m. |
| Enigma Messages with Repeated Letters — Part 5 | 100 | Oct. 18, 2015, 12:09 p.m. |
| Letter to the Templars — Part 3 | 1,115 | Oct. 17, 2015, 5:17 p.m. |
| Letter to the Templars — Part 2 | 100 | Oct. 17, 2015, 3:28 p.m. |
| Letter to the Templars — Part 1 | 100 | Oct. 17, 2015, 3:15 p.m. |
| Beaver Code | 100 | Oct. 17, 2015, 12:47 p.m. |
| Number Sequence — Part 2 | 100 | Oct. 11, 2015, 5:43 p.m. |
| Caesar Encryption | 100 | Oct. 11, 2015, 2:19 p.m. |
| Original Caesar Cipher | 100 | Oct. 11, 2015, 2:13 p.m. |
| ¿No Hablas Español? No problemo! | 100 | Oct. 11, 2015, 12:37 p.m. |
| Enigma Messages with Repeated Letters — Part 1 | 100 | Oct. 10, 2015, 4:37 p.m. |
| Number Sequence | 100 | Oct. 10, 2015, 3 p.m. |
Gold0
Silver0
Bronze0
