| Advent-Challenge — Part 2 | 1,114 | Feb. 3, 2021, 3:20 p.m. |
| Advent-Challenge — Part 1 | 100 | Feb. 2, 2021, 9:24 p.m. |
| Autokey Cipher | 100 | Feb. 2, 2021, 6:23 p.m. |
| Cryptanalysis Hacking Puzzles — Part 2 | 100 | Feb. 2, 2021, 4:47 p.m. |
| Number Sequence — Part 10 | 100 | Nov. 7, 2019, 1:11 a.m. |
| RSA Factoring Challenge: RSA-210 | 0 | Nov. 6, 2019, 10:56 p.m. |
| Image Noise | 100 | July 27, 2016, 11:49 p.m. |
| Number Sequence — Part 7 | 100 | May 12, 2016, 12:13 a.m. |
| Number Sequence — Part 8 | 103 | Oct. 21, 2015, 7:52 p.m. |
| M-138 — Part 2 | 1,279 | Feb. 15, 2015, 9:03 a.m. |
| M-138 — Part 1 | 102 | Feb. 13, 2015, 6:49 a.m. |
| Heartbleed — Part 3 | 1,200 | Feb. 5, 2015, 3:10 a.m. |
| One-Time Pad with Flaws | 100 | Jan. 26, 2015, 3:08 a.m. |
| Heartbleed — Part 2 | 101 | Jan. 25, 2015, 9:25 p.m. |
| Partial Key Exposure with RSA — Part 1 | 1,116 | Jan. 25, 2015, 7:07 p.m. |
| Heartbleed — Part 1 | 101 | Jan. 24, 2015, 3:22 p.m. |
| Enigma Messages with Repeated Letters — Part 1 | 105 | Oct. 15, 2013, 10:26 a.m. |
| BCR code (Book-Caesar-RSA) | 1,153 | Oct. 14, 2013, 7:58 p.m. |
| A really long number sequence | 1,128 | Oct. 7, 2013, 8:29 p.m. |
| Hybrid Encryption I | 1,116 | Oct. 6, 2013, 3:47 p.m. |
| Enigma Part 1 | 1,116 | Oct. 3, 2013, 3:39 p.m. |
| Enigma Combinatorics | 100 | Oct. 3, 2013, 3:05 p.m. |
| Enigma Messages | 100 | Oct. 1, 2013, 12:05 a.m. |
| Brute-Force-Attack on Triple-DES with Reduced Key Space | 1,116 | Sept. 26, 2013, 12:42 a.m. |
| Nils away on travel | 102 | Sept. 23, 2013, 8:18 p.m. |
| Reserve Hand Procedure — Part 1 | 100 | Sept. 23, 2013, 7:46 p.m. |
| From Russia with Love | 105 | Sept. 23, 2013, 5:45 p.m. |
| Snow White and the seven dwarfs | 103 | May 20, 2013, 2:31 a.m. |
| A hidden word | 108 | Jan. 17, 2013, 5:37 p.m. |
| Cracking SHA1-Hashed Passwords | 1,138 | Oct. 26, 2012, 7:34 p.m. |
| Unusual encryption using a diophantine equation | 1,152 | Oct. 21, 2012, 6:14 a.m. |
| RSA: Two different keys — same ciphertext | 1,150 | Oct. 18, 2012, 7:11 p.m. |
| Letter to the Templars — Part 3 | 2,000 | Oct. 9, 2012, 7:32 p.m. |
| Factorization Cipher — Part 1 | 100 | Sept. 30, 2012, 6:27 p.m. |
| Not-so-Secret Message from Malawi — Part I (RSA) | 1,130 | Sept. 29, 2012, 10:07 p.m. |
| Broadcasting and low exponent — RSA Attack | 1,150 | Sept. 25, 2012, 10:42 p.m. |
| Alice's Birthday Party (Part 2) | 1,130 | Sept. 25, 2012, 9:55 p.m. |
| Alice's Birthday Party (Part 1) | 1,130 | Sept. 24, 2012, 7:43 p.m. |
| Molehunt (Part 1/3) | 100 | Sept. 13, 2012, 8 p.m. |
| Monoalphabetic Substitution | 100 | Sept. 11, 2012, 10:12 p.m. |
| ¿No Hablas Español? No problemo! | 101 | Sept. 10, 2012, 10:24 p.m. |
| A modified homophonic cipher with reduced alphabets — Part 2 | 100 | Sept. 9, 2012, 7:15 p.m. |
| A modified homophonic cipher with reduced alphabets — Part 1 | 100 | Sept. 9, 2012, 5:03 p.m. |
| Grille Cipher | 100 | Sept. 9, 2012, 4:34 a.m. |
| The Book Code: A Challenge for Bookworms | 101 | Sept. 9, 2012, 2:27 a.m. |
| How do you become a big cryptographer? | 101 | Sept. 9, 2012, 12:45 a.m. |
| Modified Caesar Cipher | 100 | Aug. 26, 2012, 10:03 p.m. |
| Affine Codes / Modulo Arithmetic with N / Extended Euclid | 100 | Aug. 26, 2012, 8:17 p.m. |
| Number Sequence — Part 3 | 101 | Aug. 26, 2012, 5:36 p.m. |
| Number Sequence — Part 4 | 101 | Aug. 26, 2012, 5:09 p.m. |
| Beaver Code | 108 | Aug. 26, 2012, 4:36 p.m. |
| Letter to the Templars — Part 2 | 104 | Aug. 26, 2012, 3:53 p.m. |
| Letter to the Templars — Part 1 | 102 | Aug. 26, 2012, 2:33 a.m. |
| Number Sequence — Part 2 | 106 | July 27, 2011, 3:47 p.m. |
| Number Sequence | 100 | July 27, 2011, 3:14 p.m. |
| Classical Ciphers^3 | 100 | July 27, 2011, 2:48 p.m. |
| Original Caesar Cipher | 100 | July 27, 2011, 2:11 p.m. |
| Caesar Encryption | 100 | July 27, 2011, 2:08 p.m. |