| Snow White and the seven dwarfs | 100 | May 27, 2021, 7:01 a.m. |
| Lightweight Introduction to Lattices — Part 2 | 100 | May 19, 2021, 7:26 a.m. |
| Lightweight Introduction to Lattices — Part 1 | 100 | May 19, 2021, 6:16 a.m. |
| RSA Factoring Challenge: RSA-250 | 0 | May 12, 2021, 8:01 p.m. |
| RSA Factoring Challenge: RSA-240 | 0 | May 12, 2021, 7:59 p.m. |
| RSA Factoring Challenge: RSA-232 | 0 | May 12, 2021, 7:57 p.m. |
| Homophonic Encryption — Part 4 | 1,129 | May 12, 2021, noon |
| Homophonic Encryption — Part 3 | 1,129 | May 12, 2021, 11:50 a.m. |
| Homophonic Encryption — Part 2 | 1,129 | May 12, 2021, 11:34 a.m. |
| Homophonic Encryption — Part 1 | 1,129 | May 12, 2021, 11:30 a.m. |
| Cryptanalysis Hacking Puzzles — Part 2 | 100 | May 11, 2021, 4:31 p.m. |
| The Book Code: A Challenge for Bookworms | 100 | May 11, 2021, 8:49 a.m. |
| ADFGVX — Part 1 | 100 | May 9, 2021, 11:05 a.m. |
| Spanish Strip Cipher — Part 2 | 1,091 | May 7, 2021, 7:33 p.m. |
| Molehunt (Part 1/3) | 100 | May 6, 2021, 8:58 a.m. |
| Number Sequence — Part 7 | 100 | April 29, 2021, 12:31 p.m. |
| Number Sequence — Part 9 | 100 | April 27, 2021, 6:37 a.m. |
| Number Sequence — Part 6 | 100 | April 27, 2021, 5:48 a.m. |
| Strange Message from Thessaloniki | 100 | April 26, 2021, 7:16 a.m. |
| Letter from the Alleged Countess Julie von Ortenburg | 100 | April 23, 2021, 10:56 a.m. |
| Trifid Cipher | 100 | April 22, 2021, 3:14 p.m. |
| Wheatstone Cryptograph — Part 1 | 200 | April 22, 2021, 12:55 p.m. |
| Find the right route — Part 3 | 101 | April 21, 2021, 8:58 a.m. |
| News from Castle Mansfeld | 100 | April 19, 2021, 7:39 a.m. |
| A Secret Message from Castle Mansfeld | 100 | April 19, 2021, 7:22 a.m. |
| Image Noise | 100 | April 19, 2021, 5:19 a.m. |
| Playfair with hints about the grid | 100 | April 17, 2021, 10:23 a.m. |
| A hidden word | 100 | April 16, 2021, 7:46 a.m. |
| Modified Caesar Cipher | 100 | April 15, 2021, 6:38 p.m. |
| Affine Codes / Modulo Arithmetic with N / Extended Euclid | 100 | April 15, 2021, 6:25 a.m. |
| Classical Ciphers^3 | 100 | April 14, 2021, 11:05 a.m. |
| M-138 — Part 3 | 1,094 | April 14, 2021, 5:26 a.m. |
| M-138 — Part 2 | 1,094 | April 13, 2021, 1:17 p.m. |
| Playfair Encryption | 100 | April 13, 2021, 10:22 a.m. |
| Double Columnar Transposition | 100 | April 13, 2021, 9:28 a.m. |
| A hidden word — Part 2 | 100 | April 13, 2021, 8:50 a.m. |
| Nils away on travel | 100 | April 12, 2021, 6:50 p.m. |
| Factorization Cipher — Part 1 | 100 | April 11, 2021, 1:34 p.m. |
| The Einstein Enigma | 1,113 | April 11, 2021, 12:40 p.m. |
| How do you become a big cryptographer? | 100 | April 10, 2021, 11:52 a.m. |
| From Russia with Love | 100 | April 8, 2021, 1:01 p.m. |
| The Last Note | 100 | April 8, 2021, 12:40 p.m. |
| Autokey Cipher | 100 | April 8, 2021, 11:12 a.m. |
| Find the right route — Part 2 | 101 | April 8, 2021, 10:30 a.m. |
| ¿No Hablas Español? No problemo! | 100 | April 8, 2021, 5:26 a.m. |
| Letter to the Templars — Part 3 | 1,087 | April 7, 2021, 12:15 p.m. |
| Letter to the Templars — Part 2 | 100 | April 7, 2021, 12:01 p.m. |
| Letter to the Templars — Part 1 | 100 | April 7, 2021, 11:52 a.m. |
| Cracking SHA1-Hashed Passwords | 1,083 | April 7, 2021, 11:31 a.m. |
| Find the right route — Part 1 | 101 | April 6, 2021, 12:58 p.m. |
| M-138 — Part 1 | 100 | April 6, 2021, 10:55 a.m. |
| Number Sequence — Part 2 | 100 | April 6, 2021, 8:31 a.m. |
| Advent-Challenge — Part 1 | 100 | April 6, 2021, 5:07 a.m. |
| Number Sequence — Part 8 | 100 | April 5, 2021, 4:21 p.m. |
| Beaver Code | 100 | April 5, 2021, 12:07 p.m. |
| Number Sequence — Part 5 | 100 | April 5, 2021, 11:01 a.m. |
| Number Sequence — Part 4 | 100 | April 5, 2021, 10:07 a.m. |
| Number Sequence — Part 3 | 100 | April 5, 2021, 10:04 a.m. |
| Grille Cipher | 100 | April 4, 2021, 8:28 p.m. |
| Original Caesar Cipher | 100 | April 4, 2021, 6:27 p.m. |
| Caesar Encryption | 100 | April 4, 2021, 5:46 p.m. |
| Number Sequence | 100 | April 4, 2021, 4:14 p.m. |
| Monoalphabetic Substitution | 100 | April 4, 2021, 7:56 a.m. |