Quickstart

In this section we will build and run a fibonacci program.

Setup

First, create a new Rust project.

cargo init fibonacci

In Cargo.toml, add the following dependency:

[dependencies]
openvm = { git = "https://github.com/openvm-org/openvm.git", features = ["std"] }

Note that std is not enabled by default, so explicitly enabling it is required.

The fibonacci program

The read function takes input from the stdin (it also works with OpenVM runtime).

// src/main.rs
use openvm::io::{read, reveal};

openvm::entry!(main);

fn main() {
    let n: u64 = read();
    let mut a: u64 = 0;
    let mut b: u64 = 1;
    for _ in 0..n {
        let c: u64 = a.wrapping_add(b);
        a = b;
        b = c;
    }
    reveal(a as u32, 0);
    reveal((a >> 32) as u32, 1);
}

Build

To build the program, run:

cargo openvm build

This will output an OpenVM executable file to ./openvm/app.vmexe.

Keygen

Before generating any proofs, we will also need to generate the proving and verification keys.

cargo openvm keygen

This will output a serialized proving key to ./openvm/app.pk and a verification key to ./openvm/app.vk.

Proof Generation

Now we are ready to generate a proof! Simply run:

OPENVM_FAST_TEST=1 cargo openvm prove app --input "0x0A00000000000000"

The --input field is passed to the program which receives it via the io::read function. In our main.rs we called read() to get n: u64. The input here is n = 100u64 in little endian. Note that this value must be padded to exactly 8 bytes (64 bits).

The serialized proof will be output to ./openvm/app.proof.

The OPENVM_FAST_TEST environment variable is used to enable fast proving for testing purposes. To run with proof with secure parameters, remove the environmental variable.

Proof Verification

Finally, the proof can be verified.

cargo openvm verify app

The process should exit with no errors.

Runtime Execution

If necessary, the executable can also be run without proof generation. This can be useful for testing purposes.

cargo openvm run --input "0x0A00000000000000"

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