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                     C  T  F

Cryptography · Smart Contracts · Zero-Knowledge Proofs

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Challenges

#	Name	Category	Difficulty	Points	# of solves
1	Fractured Lattices	Crypto / Forensics	Hard	500	02
2	Siege Protocol	Smart Contracts	Medium	250	08
3	Operation Phantom Proof	ZK / STARK	Hard	500	07

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Challenge Summaries

1 — Fractured Lattices

The lattice remembers what the cipher forgot.

An LWE encryption scheme protects a flag. The matrix is derived from a secret prime — but the prime was shattered into fragments and hidden in plain sight. Recover the pieces, reconstruct the lattice, and break the cipher.

Skills: forensics, lattice cryptography, LLL reduction

2 — Siege Protocol

The chain remembers every king — but only one rules forever.

A DeFi kingdom on Sepolia where challengers fight for the throne and the treasury funds loans. Two vulnerabilities must be chained: lock the throne permanently via a refund DoS, then drain the treasury through a batch collateral bypass.

Skills: Solidity, smart contract exploitation, Foundry

3 — Operation Phantom Proof

Trust nothing. Verify everything. Unless the verifier is broken.

A custom STARK prover/verifier for Rescue-Prime hashes over BabyBear. Find the soundness bug in the verifier and forge a valid proof for a false statement. Submit it to the oracle for the flag.

Skills: zero-knowledge proofs, STARK internals, Rust

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Structure

kronos-ctf/
├── chall_1_fractured_lattices/
│   ├── chall_1/              # participant files (cipher.txt)
│   └── chall_1_writeup/      # solution writeup
├── chall_2_block_participants/
│   ├── chall_2/              # participant Foundry project
│   └── chall_2_writeup/      # solution writeup
├── chall_3_op_phantom_proof/
│   ├── chall_3/              # participant Rust project
│   └── chall_3_writeup/      # solution writeup
└── README.md

Each challenge directory contains:

• chall_N/ — files distributed to participants
• chall_N_writeup/ — organizer solution writeup

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Rules

• You may use any tools, languages, or frameworks.
• You may deploy your own contracts (challenge 2).
• You may not brute-force oracle endpoints.
• You may not attack infrastructure.
• Flag format: tryst{...} or as specified per challenge.

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Getting Started

git clone <repo-url>
cd kronos-ctf

# Challenge 1 — just needs Python + SageMath
cat chall_1_fractured_lattices/chall_1/cipher.txt

# Challenge 2 — needs Foundry + Sepolia ETH
cd chall_2_block_participants/chall_2
forge build

# Challenge 3 — needs Rust
cd chall_3_op_phantom_proof/chall_3
cargo build --release

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Good luck. The clock is ticking.