ZK Verified Project Euler Solutions in Rust

Repo for storing my Project Euler Rust solutions. Each solution encrypted and accompanied by a zk proof generated by RISC Zero's zkVM, proving its correctness. I know this is complete overkill and unnecessary but I thought it was cool.

How it works

1. Each solution runs inside RISC Zero's zkVM, a RISC-V virtual machine
2. The zkVM produces a receipt, which is a cryptographic proof that the program executed correctly and output a specific answer
3. The receipt is tied to an image ID, a hash of the guest program binary. This commits to the code without revealing it
4. Anyone with the receipt and image ID can verify the proof

The proof guarantees: "There exists a program (identified by this image ID) that, given this problem number, outputs this answer." You can confirm the answer is correct by checking it against Project Euler, but you cannot determine how it was computed.

Verifying the proofs

Not all proofs might be available because they take a long time to generate, with which I'd rather not burden my silicon.

Prerequisites

• Rust (stable)
• RISC Zero toolchain: curl -L https://risczero.com/install | bash && rzup install

Verify

# Verify a single problem
cargo run -p verify -- 1

# Verify all proofs
cargo run -p verify -- all

CLI usage

There are three binaries in this workspace:

project-euler — takes a single problem number; prints the answer and execution time.

cargo run -p project-euler --release -- <problem_number>

host — generate ZK proofs

cargo run -p host -- <problem_number|all>

verify — verify ZK proofs

cargo run -p verify -- <problem_number|all>

Adding a new problem

Create src/problems/p###.rs (zero-padded, e.g. p019.rs) with one of these signatures:

pub fn solve() -> String           // self-contained problems
pub fn solve_with_input(input: &str) -> String  // problems needing external data (put input in inputs/p###.txt)

The build script then auto-discovers new files and wires everything up. NOTE: Any change to the ELF binary, including adding new solutions, invalidates all existing proofs. I recommend just doing a few; 1,2, and 6 are quick to prove, for example.

Proof generation times

Problem	Rough proof time (m3 pro)
1	<10s
2	<10s
3	~5h
4	not generated yet (tried for 6 hours and it didn't finish)
5	not generated yet
6	<10s
7	not generated yet
8	not generated yet
9	not generated yet
10	not generated yet
11	not generated yet
12	not generated yet
13	not generated yet
14	not generated yet
15	not generated yet
16	not generated yet
17	not generated yet
18	not generated yet
19	not generated yet
20	not generated yet
21	not generated yet
22	not generated yet
23	not generated yet
27	not generated yet
34	not generated yet
35	not generated yet
50	not generated yet
67	not generated yet
92	not generated yet

Project structure

zk-euler/
├── proofs/                 # Cryptographic receipts
│   ├── image_id.json       # Hash of the guest program
│   └── p001.bin ...        # STARK proofs for each problem
├── verify/                 # Public verifier
│   └── src/main.rs
├── host/                   # Proof generator (encrypted)
│   └── src/main.rs
├── methods/                # zkVM guest build infrastructure
│   └── guest/src/main.rs   # Guest entry point (encrypted)
├── src/                    # Solution code (encrypted)
│   ├── main.rs             # CLI: cargo run -p project-euler -- <n>
│   ├── lib.rs
│   ├── utils/              # Shared utilities
│   │   ├── primes.rs
│   │   ├── digits.rs
│   │   └── math.rs
│   └── problems/           
└── inputs/                 # Problem input data files