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 | 172 solves |

Mathematics | Roll your Own | 125 | 113 solves |

Symmetric Ciphers | Dancing Queen | 120 | 112 solves |

General | SSH Keys | 35 | 967 solves |

Misc | LFSR Destroyer | 250 | 33 solves |

Hash Functions | Hash Stuffing | 50 | 184 solves |

Elliptic Curves | Montgomery's Ladder | 40 | 164 solves |

Elliptic Curves | Double and Broken | 50 | 110 solves |

Diffie-Hellman | The Matrix Revolutions | 125 | 64 solves |

Diffie-Hellman | The Matrix Reloaded | 100 | 98 solves |

Diffie-Hellman | The Matrix | 75 | 144 solves |

Crypto on the Web | JSON in JSON | 40 | 655 solves |

Symmetric Ciphers | Oh SNAP | 120 | 138 solves |

Misc | L-Win | 120 | 110 solves |

Misc | Bruce Schneier's Password: Part 2 | 250 | 46 solves |

Misc | Bruce Schneier's Password | 100 | 162 solves |

Hash Functions | Mixed Up | 120 | 140 solves |

Crypto on the Web | RSA or HMAC? | 35 | 740 solves |

Crypto on the Web | JWT Secrets | 25 | 994 solves |

Crypto on the Web | No Way JOSE | 20 | 1086 solves |

Hash Functions | Jack's Birthday Hash | 20 | 706 solves |

Hash Functions | Jack's Birthday Confusion | 30 | 712 solves |

Crypto on the Web | Token Appreciation | 5 | 1695 solves |

Crypto on the Web | JWT Sessions | 10 | 1370 solves |

Mathematics | Cofactor Cofantasy | 150 | 184 solves |

Symmetric Ciphers | Logon Zero | 80 | 279 solves |

RSA | RSA Backdoor Viability | 175 | 308 solves |

Misc | Jeff's LFSR | 150 | 100 solves |

General | Transparency | 50 | 1787 solves |

RSA | Let's Decrypt Again | 175 | 120 solves |

Hash Functions | Twin Keys | 100 | 123 solves |

Hash Functions | Invariant | 250 | 73 solves |

Hash Functions | No Difference | 175 | 140 solves |

Misc | Trust Games | 150 | 100 solves |

Hash Functions | PriMeD5 | 100 | 166 solves |

Mathematics | Ellipse Curve Cryptography | 125 | 209 solves |

RSA | Let's Decrypt | 80 | 272 solves |

Elliptic Curves | No Random, No Bias | 120 | 132 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 136 solves |

Mathematics | Size and Basis | 15 | 1685 solves |

Mathematics | Gaussian Reduction | 50 | 1018 solves |

Mathematics | Find the Lattice | 100 | 548 solves |

Mathematics | Vectors | 10 | 1753 solves |

Mathematics | Backpack Cryptography | 120 | 326 solves |

Mathematics | Gram Schmidt | 30 | 1125 solves |

Mathematics | What's a Lattice? | 40 | 1248 solves |

Mathematics | Unencryptable | 125 | 381 solves |

Misc | Too Many Errors | 100 | 151 solves |

Symmetric Ciphers | Forbidden Fruit | 150 | 197 solves |

Hash Functions | Collider | 50 | 540 solves |

Category | Challenge | Points | Solves |

Misc | LFSR Destroyer | 250 | 33 solves |

Misc | Bruce Schneier's Password: Part 2 | 250 | 46 solves |

Diffie-Hellman | The Matrix Revolutions | 125 | 64 solves |

Hash Functions | Invariant | 250 | 73 solves |

Diffie-Hellman | The Matrix Reloaded | 100 | 98 solves |

Misc | Jeff's LFSR | 150 | 100 solves |

Misc | Trust Games | 150 | 100 solves |

Misc | L-Win | 120 | 110 solves |

Elliptic Curves | Double and Broken | 50 | 110 solves |

Symmetric Ciphers | Dancing Queen | 120 | 112 solves |

Mathematics | Roll your Own | 125 | 113 solves |

RSA | Let's Decrypt Again | 175 | 120 solves |

Hash Functions | Twin Keys | 100 | 123 solves |

Elliptic Curves | No Random, No Bias | 120 | 132 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 136 solves |

Symmetric Ciphers | Oh SNAP | 120 | 138 solves |

Hash Functions | Mixed Up | 120 | 140 solves |

Hash Functions | No Difference | 175 | 140 solves |

Diffie-Hellman | The Matrix | 75 | 144 solves |

Misc | Nothing Up My Sleeve | 150 | 147 solves |

Misc | Too Many Errors | 100 | 151 solves |

Misc | Bruce Schneier's Password | 100 | 162 solves |

Elliptic Curves | Montgomery's Ladder | 40 | 164 solves |

Hash Functions | PriMeD5 | 100 | 166 solves |

Crypto on the Web | RSA or HMAC? Part 2 | 100 | 172 solves |

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