This page contains lists of recent and most difficult challenges. To play the challenges, please go to the challenges section.

Category | Challenge | Points | Solves |

Crypto on the Web | RSA or HMAC? Part 2 | 100 | 141 solves |

Mathematics | Roll your Own | 90 | 88 solves |

Symmetric Ciphers | Dancing Queen | 120 | 97 solves |

General | SSH Keys | 35 | 758 solves |

Misc | LFSR Destroyer | 250 | 27 solves |

Hash Functions | Hash Stuffing | 50 | 129 solves |

Elliptic Curves | Montgomery's Ladder | 40 | 111 solves |

Elliptic Curves | Double and Broken | 50 | 89 solves |

Diffie-Hellman | The Matrix Revolutions | 125 | 43 solves |

Diffie-Hellman | The Matrix Reloaded | 100 | 70 solves |

Diffie-Hellman | The Matrix | 75 | 110 solves |

Crypto on the Web | JSON in JSON | 40 | 591 solves |

Symmetric Ciphers | Oh SNAP | 120 | 124 solves |

Misc | L-Win | 120 | 99 solves |

Misc | Bruce Schneier's Password: Part 2 | 250 | 39 solves |

Misc | Bruce Schneier's Password | 100 | 144 solves |

Hash Functions | Mixed Up | 120 | 119 solves |

Crypto on the Web | RSA or HMAC? | 35 | 684 solves |

Crypto on the Web | JWT Secrets | 25 | 903 solves |

Crypto on the Web | No Way JOSE | 20 | 980 solves |

Hash Functions | Jack's Birthday Hash | 20 | 638 solves |

Hash Functions | Jack's Birthday Confusion | 30 | 641 solves |

Crypto on the Web | Token Appreciation | 5 | 1515 solves |

Crypto on the Web | JWT Sessions | 10 | 1236 solves |

Mathematics | Cofactor Cofantasy | 150 | 157 solves |

Symmetric Ciphers | Logon Zero | 80 | 232 solves |

RSA | RSA Backdoor Viability | 175 | 268 solves |

Misc | Jeff's LFSR | 150 | 91 solves |

General | Transparency | 50 | 1644 solves |

RSA | Let's Decrypt Again | 175 | 109 solves |

Hash Functions | Twin Keys | 100 | 109 solves |

Hash Functions | Invariant | 250 | 67 solves |

Hash Functions | No Difference | 175 | 122 solves |

Misc | Trust Games | 150 | 93 solves |

Hash Functions | PriMeD5 | 100 | 146 solves |

Mathematics | Ellipse Curve Cryptography | 125 | 186 solves |

RSA | Let's Decrypt | 80 | 243 solves |

Elliptic Curves | No Random, No Bias | 120 | 119 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 122 solves |

Mathematics | Size and Basis | 15 | 1502 solves |

Mathematics | Gaussian Reduction | 50 | 915 solves |

Mathematics | Find the Lattice | 100 | 486 solves |

Mathematics | Vectors | 10 | 1554 solves |

Mathematics | Backpack Cryptography | 120 | 289 solves |

Mathematics | Gram Schmidt | 30 | 997 solves |

Mathematics | What's a Lattice? | 40 | 1108 solves |

Mathematics | Unencryptable | 125 | 342 solves |

Misc | Too Many Errors | 100 | 142 solves |

Symmetric Ciphers | Forbidden Fruit | 150 | 188 solves |

Hash Functions | Collider | 50 | 477 solves |

Category | Challenge | Points | Solves |

Misc | LFSR Destroyer | 250 | 27 solves |

Misc | Bruce Schneier's Password: Part 2 | 250 | 39 solves |

Diffie-Hellman | The Matrix Revolutions | 125 | 43 solves |

Hash Functions | Invariant | 250 | 67 solves |

Diffie-Hellman | The Matrix Reloaded | 100 | 70 solves |

Mathematics | Roll your Own | 90 | 88 solves |

Elliptic Curves | Double and Broken | 50 | 89 solves |

Misc | Jeff's LFSR | 150 | 91 solves |

Misc | Trust Games | 150 | 93 solves |

Symmetric Ciphers | Dancing Queen | 120 | 97 solves |

Misc | L-Win | 120 | 99 solves |

Hash Functions | Twin Keys | 100 | 109 solves |

RSA | Let's Decrypt Again | 175 | 109 solves |

Diffie-Hellman | The Matrix | 75 | 110 solves |

Elliptic Curves | Montgomery's Ladder | 40 | 111 solves |

Hash Functions | Mixed Up | 120 | 119 solves |

Elliptic Curves | No Random, No Bias | 120 | 119 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 122 solves |

Hash Functions | No Difference | 175 | 122 solves |

Symmetric Ciphers | Oh SNAP | 120 | 124 solves |

Hash Functions | Hash Stuffing | 50 | 129 solves |

Misc | Nothing Up My Sleeve | 150 | 138 solves |

Crypto on the Web | RSA or HMAC? Part 2 | 100 | 141 solves |

Misc | Too Many Errors | 100 | 142 solves |

Misc | Bruce Schneier's Password | 100 | 144 solves |

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