| Find the right route — Part 1 | 107 | Nov. 11, 2020, 2:07 p.m. |
| Modified Caesar Cipher | 100 | Nov. 11, 2020, 2:04 p.m. |
| Number Sequence — Part 6 | 100 | Feb. 12, 2018, 12:44 p.m. |
| Enigma Messages with Repeated Letters — Part 1 | 200 | Sept. 26, 2013, 9:56 p.m. |
| Alice's Birthday Party (Part 2) | 1,139 | April 26, 2012, 10:20 p.m. |
| Alice's Birthday Party (Part 1) | 1,139 | April 26, 2012, 10:02 p.m. |
| Turing Bombe Enigma I | 101 | April 26, 2012, 7:26 p.m. |
| Pigpen with a twist — Part 2 | 1,178 | April 25, 2012, 9:02 p.m. |
| Number Sequence — Part 5 | 114 | April 25, 2012, 1:36 a.m. |
| Number Sequence — Part 4 | 114 | April 25, 2012, 1:35 a.m. |
| Double Columnar Transposition | 101 | April 22, 2012, 10:19 p.m. |
| Grille Cipher | 101 | April 22, 2012, 10:18 p.m. |
| Smartcard RSA | 1,140 | April 22, 2012, 10:03 p.m. |
| Cracking SHA1-Hashed Passwords | 1,155 | April 21, 2012, 2:18 p.m. |
| A Secret Message from Castle Mansfeld | 100 | April 21, 2012, 2:06 p.m. |
| Partial Key Exposure with RSA — Part 1 | 1,258 | April 20, 2012, 9:27 p.m. |
| Not-so-Secret Message from Malawi — Part I (RSA) | 1,140 | April 20, 2012, 9:21 p.m. |
| Post-Quantum Cryptography: Unbalanced Oil and Vinegar System — Part 1 | 100 | April 20, 2012, 8:42 p.m. |
| Not-so-Secret Message from Malawi — Part II (ECC) | 1,140 | April 19, 2012, 10:15 p.m. |
| Pigpen with a twist — Part 3 | 1,180 | April 19, 2012, 9:30 p.m. |
| ¿No Hablas Español? No problemo! | 200 | April 18, 2012, 10:51 p.m. |
| Affine Codes / Modulo Arithmetic with N / Extended Euclid | 100 | April 13, 2012, 12:12 p.m. |
| ECDH-Key Exchange for Beginners | 102 | April 13, 2012, 12:10 p.m. |
| The Book Code: A Challenge for Bookworms | 104 | April 13, 2012, 12:07 p.m. |
| Number Sequence | 100 | April 12, 2012, 1:27 p.m. |
| Number Sequence — Part 2 | 100 | April 12, 2012, 1:25 p.m. |
| Number Sequence — Part 3 | 108 | April 12, 2012, 1:23 p.m. |