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? | 35 | 100 solves |

Crypto on the Web | JWT Secrets | 25 | 116 solves |

Crypto on the Web | No Way JOSE | 20 | 123 solves |

Mathematics | Jack's Birthday Hash | 20 | 74 solves |

Mathematics | Jack's Birthday Confusion | 30 | 91 solves |

Crypto on the Web | Token Appreciation | 5 | 175 solves |

Crypto on the Web | JWT Sessions | 10 | 141 solves |

Mathematics | Cofactor Cofantasy | 200 | 31 solves |

Block Ciphers | Logon Zero | 80 | 49 solves |

RSA | RSA Backdoor Viability | 175 | 22 solves |

Misc | Jeff's LFSR | 150 | 19 solves |

General | Transparency | 50 | 379 solves |

RSA | Let's Decrypt Again | 175 | 43 solves |

Misc | Twin Keys | 100 | 38 solves |

Misc | Invariant | 250 | 28 solves |

Misc | No Difference | 175 | 39 solves |

Misc | Trust Games | 150 | 38 solves |

Misc | PriMeD5 | 100 | 67 solves |

Mathematics | Ellipse Curve Cryptography | 125 | 66 solves |

RSA | Let's Decrypt | 80 | 89 solves |

Elliptic Curves | No Random, No Bias | 120 | 51 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 42 solves |

Mathematics | Size and Basis | 15 | 606 solves |

Mathematics | Gaussian Reduction | 50 | 366 solves |

Mathematics | Find the Lattice | 100 | 198 solves |

Mathematics | Vectors | 10 | 627 solves |

Mathematics | Backpack Cryptography | 120 | 120 solves |

Mathematics | Gram Schmidt | 30 | 396 solves |

Mathematics | What's a Lattice? | 40 | 433 solves |

Mathematics | Unencryptable | 125 | 138 solves |

Misc | Too Many Errors | 100 | 79 solves |

Block Ciphers | Forbidden Fruit | 150 | 88 solves |

Misc | Collider | 50 | 207 solves |

Misc | MD0 | 80 | 115 solves |

Block Ciphers | Triple DES | 60 | 135 solves |

Mathematics | Modular Square Root | 35 | 671 solves |

Mathematics | Broken RSA | 100 | 239 solves |

Mathematics | Real Eisenstein | 150 | 92 solves |

Block Ciphers | Keyed Permutations | 5 | 1078 solves |

Block Ciphers | Structure of AES | 15 | 758 solves |

Block Ciphers | Round Keys | 20 | 697 solves |

Block Ciphers | Resisting Bruteforce | 10 | 989 solves |

Block Ciphers | Confusion through Substitution | 25 | 607 solves |

Block Ciphers | Bringing It All Together | 50 | 430 solves |

Block Ciphers | Diffusion through Permutation | 30 | 549 solves |

RSA | Bespoke Padding | 100 | 144 solves |

Misc | Nothing Up My Sleeve | 150 | 82 solves |

Elliptic Curves | Moving Problems | 150 | 97 solves |

Block Ciphers | Paper Plane | 120 | 131 solves |

Mathematics | Prime and Prejudice | 200 | 109 solves |

Category | Challenge | Points | Solves |

Misc | Jeff's LFSR | 150 | 19 solves |

RSA | RSA Backdoor Viability | 175 | 22 solves |

Misc | Invariant | 250 | 28 solves |

Mathematics | Cofactor Cofantasy | 200 | 31 solves |

Misc | Twin Keys | 100 | 38 solves |

Misc | Trust Games | 150 | 38 solves |

Misc | No Difference | 175 | 39 solves |

Elliptic Curves | Edwards Goes Degenerate | 100 | 42 solves |

RSA | Let's Decrypt Again | 175 | 43 solves |

Block Ciphers | Logon Zero | 80 | 49 solves |

Elliptic Curves | No Random, No Bias | 120 | 51 solves |

Mathematics | Ellipse Curve Cryptography | 125 | 66 solves |

Misc | PriMeD5 | 100 | 67 solves |

Mathematics | Jack's Birthday Hash | 20 | 74 solves |

Misc | Too Many Errors | 100 | 79 solves |

Misc | Nothing Up My Sleeve | 150 | 82 solves |

Block Ciphers | Forbidden Fruit | 150 | 88 solves |

RSA | Let's Decrypt | 80 | 89 solves |

Mathematics | Jack's Birthday Confusion | 30 | 91 solves |

Mathematics | Real Eisenstein | 150 | 92 solves |

Elliptic Curves | Moving Problems | 150 | 97 solves |

Crypto on the Web | RSA or HMAC? | 35 | 100 solves |

Misc | Toshi's Treasure | 150 | 108 solves |

Mathematics | Prime and Prejudice | 200 | 109 solves |

Elliptic Curves | Elliptic Nodes | 150 | 111 solves |

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