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 | 213 solves |

Mathematics | Roll your Own | 125 | 134 solves |

Symmetric Ciphers | Dancing Queen | 120 | 151 solves |

General | SSH Keys | 35 | 1133 solves |

Misc | LFSR Destroyer | 250 | 39 solves |

Hash Functions | Hash Stuffing | 50 | 226 solves |

Elliptic Curves | Montgomery's Ladder | 40 | 207 solves |

Elliptic Curves | Double and Broken | 50 | 134 solves |

Diffie-Hellman | The Matrix Revolutions | 125 | 94 solves |

Diffie-Hellman | The Matrix Reloaded | 100 | 141 solves |

Diffie-Hellman | The Matrix | 75 | 200 solves |

Crypto on the Web | JSON in JSON | 40 | 714 solves |

Symmetric Ciphers | Oh SNAP | 120 | 161 solves |

Misc | L-Win | 120 | 130 solves |

Misc | Bruce Schneier's Password: Part 2 | 250 | 65 solves |

Misc | Bruce Schneier's Password | 100 | 190 solves |

Hash Functions | Mixed Up | 120 | 170 solves |

Crypto on the Web | RSA or HMAC? | 35 | 808 solves |

Crypto on the Web | JWT Secrets | 25 | 1075 solves |

Crypto on the Web | No Way JOSE | 20 | 1181 solves |

Hash Functions | Jack's Birthday Hash | 20 | 782 solves |

Hash Functions | Jack's Birthday Confusion | 30 | 774 solves |

Crypto on the Web | Token Appreciation | 5 | 1829 solves |

Crypto on the Web | JWT Sessions | 10 | 1480 solves |

Mathematics | Cofactor Cofantasy | 150 | 214 solves |

Symmetric Ciphers | Logon Zero | 80 | 321 solves |

RSA | RSA Backdoor Viability | 175 | 364 solves |

Misc | Jeff's LFSR | 150 | 119 solves |

General | Transparency | 50 | 1900 solves |

RSA | Let's Decrypt Again | 175 | 135 solves |

Hash Functions | Twin Keys | 100 | 148 solves |

Hash Functions | Invariant | 250 | 84 solves |

Hash Functions | No Difference | 175 | 171 solves |

Misc | Trust Games | 150 | 112 solves |

Hash Functions | PriMeD5 | 100 | 198 solves |

Mathematics | Ellipse Curve Cryptography | 125 | 235 solves |

RSA | Let's Decrypt | 80 | 306 solves |

Elliptic Curves | No Random, No Bias | 120 | 150 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 157 solves |

Mathematics | Size and Basis | 15 | 1792 solves |

Mathematics | Gaussian Reduction | 50 | 1097 solves |

Mathematics | Find the Lattice | 100 | 594 solves |

Mathematics | Vectors | 10 | 1871 solves |

Mathematics | Backpack Cryptography | 120 | 357 solves |

Mathematics | Gram Schmidt | 30 | 1205 solves |

Mathematics | What's a Lattice? | 40 | 1327 solves |

Mathematics | Unencryptable | 125 | 423 solves |

Misc | Too Many Errors | 100 | 172 solves |

Symmetric Ciphers | Forbidden Fruit | 150 | 221 solves |

Hash Functions | Collider | 50 | 590 solves |

Category | Challenge | Points | Solves |

Misc | LFSR Destroyer | 250 | 39 solves |

Misc | Bruce Schneier's Password: Part 2 | 250 | 65 solves |

Hash Functions | Invariant | 250 | 84 solves |

Diffie-Hellman | The Matrix Revolutions | 125 | 94 solves |

Misc | Trust Games | 150 | 112 solves |

Misc | Jeff's LFSR | 150 | 119 solves |

Misc | L-Win | 120 | 130 solves |

Mathematics | Roll your Own | 125 | 134 solves |

Elliptic Curves | Double and Broken | 50 | 134 solves |

RSA | Let's Decrypt Again | 175 | 135 solves |

Diffie-Hellman | The Matrix Reloaded | 100 | 141 solves |

Hash Functions | Twin Keys | 100 | 148 solves |

Elliptic Curves | No Random, No Bias | 120 | 150 solves |

Symmetric Ciphers | Dancing Queen | 120 | 151 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 157 solves |

Symmetric Ciphers | Oh SNAP | 120 | 161 solves |

Misc | Nothing Up My Sleeve | 150 | 164 solves |

Hash Functions | Mixed Up | 120 | 170 solves |

Hash Functions | No Difference | 175 | 171 solves |

Misc | Too Many Errors | 100 | 172 solves |

Misc | Bruce Schneier's Password | 100 | 190 solves |

Hash Functions | PriMeD5 | 100 | 198 solves |

Diffie-Hellman | The Matrix | 75 | 200 solves |

Elliptic Curves | Montgomery's Ladder | 40 | 207 solves |

Misc | Toshi's Treasure | 150 | 210 solves |

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