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 | 264 solves |

Mathematics | Roll your Own | 125 | 165 solves |

Symmetric Ciphers | Dancing Queen | 120 | 187 solves |

General | SSH Keys | 35 | 1484 solves |

Misc | LFSR Destroyer | 250 | 53 solves |

Hash Functions | Hash Stuffing | 50 | 282 solves |

Elliptic Curves | Montgomery's Ladder | 40 | 288 solves |

Elliptic Curves | Double and Broken | 50 | 162 solves |

Diffie-Hellman | The Matrix Revolutions | 125 | 108 solves |

Diffie-Hellman | The Matrix Reloaded | 100 | 170 solves |

Diffie-Hellman | The Matrix | 75 | 240 solves |

Crypto on the Web | JSON in JSON | 40 | 804 solves |

Symmetric Ciphers | Oh SNAP | 120 | 186 solves |

Misc | L-Win | 120 | 155 solves |

Misc | Bruce Schneier's Password: Part 2 | 250 | 77 solves |

Misc | Bruce Schneier's Password | 100 | 215 solves |

Hash Functions | Mixed Up | 120 | 192 solves |

Crypto on the Web | RSA or HMAC? | 35 | 895 solves |

Crypto on the Web | JWT Secrets | 25 | 1208 solves |

Crypto on the Web | No Way JOSE | 20 | 1332 solves |

Hash Functions | Jack's Birthday Hash | 20 | 902 solves |

Hash Functions | Jack's Birthday Confusion | 30 | 858 solves |

Crypto on the Web | Token Appreciation | 5 | 2075 solves |

Crypto on the Web | JWT Sessions | 10 | 1670 solves |

Mathematics | Cofactor Cofantasy | 150 | 238 solves |

Symmetric Ciphers | Logon Zero | 80 | 375 solves |

RSA | RSA Backdoor Viability | 175 | 436 solves |

Misc | Jeff's LFSR | 150 | 132 solves |

General | Transparency | 50 | 2192 solves |

RSA | Let's Decrypt Again | 175 | 154 solves |

Hash Functions | Twin Keys | 100 | 169 solves |

Hash Functions | Invariant | 250 | 98 solves |

Hash Functions | No Difference | 175 | 194 solves |

Misc | Trust Games | 150 | 127 solves |

Hash Functions | PriMeD5 | 100 | 224 solves |

Mathematics | Ellipse Curve Cryptography | 125 | 258 solves |

RSA | Let's Decrypt | 80 | 345 solves |

Elliptic Curves | No Random, No Bias | 120 | 171 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 181 solves |

Mathematics | Size and Basis | 15 | 1986 solves |

Mathematics | Gaussian Reduction | 50 | 1229 solves |

Mathematics | Find the Lattice | 100 | 668 solves |

Mathematics | Vectors | 10 | 2073 solves |

Mathematics | Backpack Cryptography | 120 | 392 solves |

Mathematics | Gram Schmidt | 30 | 1349 solves |

Mathematics | What's a Lattice? | 40 | 1471 solves |

Mathematics | Unencryptable | 125 | 469 solves |

Misc | Too Many Errors | 100 | 189 solves |

Symmetric Ciphers | Forbidden Fruit | 150 | 240 solves |

Hash Functions | Collider | 50 | 665 solves |

Category | Challenge | Points | Solves |

Misc | LFSR Destroyer | 250 | 53 solves |

Misc | Bruce Schneier's Password: Part 2 | 250 | 77 solves |

Hash Functions | Invariant | 250 | 98 solves |

Diffie-Hellman | The Matrix Revolutions | 125 | 108 solves |

Misc | Trust Games | 150 | 127 solves |

Misc | Jeff's LFSR | 150 | 132 solves |

RSA | Let's Decrypt Again | 175 | 154 solves |

Misc | L-Win | 120 | 155 solves |

Elliptic Curves | Double and Broken | 50 | 162 solves |

Mathematics | Roll your Own | 125 | 165 solves |

Hash Functions | Twin Keys | 100 | 169 solves |

Diffie-Hellman | The Matrix Reloaded | 100 | 170 solves |

Elliptic Curves | No Random, No Bias | 120 | 171 solves |

Misc | Nothing Up My Sleeve | 150 | 179 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 181 solves |

Symmetric Ciphers | Oh SNAP | 120 | 186 solves |

Symmetric Ciphers | Dancing Queen | 120 | 187 solves |

Misc | Too Many Errors | 100 | 189 solves |

Hash Functions | Mixed Up | 120 | 192 solves |

Hash Functions | No Difference | 175 | 194 solves |

Misc | Bruce Schneier's Password | 100 | 215 solves |

Hash Functions | PriMeD5 | 100 | 224 solves |

Misc | Toshi's Treasure | 150 | 230 solves |

Mathematics | Cofactor Cofantasy | 150 | 238 solves |

Symmetric Ciphers | Forbidden Fruit | 150 | 240 solves |

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