lssa-zkvm-testing/chacha20-demo/tests/proof_works.rs

use methods::*;

use risc0_zkvm::{default_prover, ExecutorEnv};

// Host-side ChaCha20
use chacha20::{ChaCha20, Key, Nonce};
use cipher::{KeyIvInit, StreamCipher};

#[test]
fn proof_works_and_matches_host_chacha() {
    // Inputs (must match what your guest expects)
    let key = [0x42u8; 32];
    let nonce = [0x24u8; 12];
    let plaintext = b"Hello, RISC Zero ChaCha20 demo!";

    // Prove with the R0 guest
    let env = ExecutorEnv::builder()
        .write(&key)
        .unwrap()
        .write(&nonce)
        .unwrap()
        .write(&plaintext.to_vec())
        .unwrap()
        .build()
        .unwrap();

    let prove_info = default_prover()
        .prove(env, GUEST_ELF)
        .expect("prove failed");
    prove_info.receipt.verify(GUEST_ID).expect("verify failed");

    // Ciphertext produced by the guest
    let guest_ct = prove_info.receipt.journal.bytes.clone();

    // Host-side reference: ChaCha20 with the same key/nonce
    let mut host_ct = plaintext.to_vec();
    let key = Key::from_slice(&key);
    let nonce = Nonce::from_slice(&nonce);
    let mut cipher = ChaCha20::new(key, nonce);
    cipher.apply_keystream(&mut host_ct);

    // Compare
    assert_eq!(
        guest_ct, host_ct,
        "guest ciphertext != host ChaCha20 ciphertext"
    );
}