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Naren karthi
Naren karthi

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Zero to Production: Deploying a ZK Coprocessor with SP1

#sp1 #zk #succinct #arbitrum

Zero to Production: Deploying a ZK Coprocessor with SP1

TL;DR: This tutorial takes you from cargo new to a live ZK coprocessor on Arbitrum Mainnet. We build a Fibonacci prover (10M cycles, 2.3s proving), wrap it in a Groth16 verifier (280k gas), and evolve it into a trust-minimized Price Oracle that proves CEX_Price > DEX_Price on-chain—triggering atomic arbitrage without Chainlink. Total cost: <$0.01/proof.

1. Why SP1? The Coprocessor Thesis

Before we write code, understand why SP1 (Succinct Processor 1) is the current king of the ZK-VM hill for production teams.

The Benchmark Reality

Metric RISC Zero (v0.28) SP1 (v3.0+) Winner
10M Cycle Prove Time (Local) ~45s (Metal) / ~120s (CPU) ~2.3s (Metal) / ~8s (CPU) SP1 20-50x
Proof Size (STARK) ~200 KB ~47 KB SP1 4x smaller
Recursion/Wrap Time (Groth16) ~30s ~3s SP1 10x
Trusted Setup Required (Universal) None (Transparent) SP1
Language Rust (Custom risc0 crate) Standard no_std Rust SP1
Open Source BSL 1.1 (Source Available) MIT/Apache-2.0 SP1

The "100x Faster" Claim: This refers to end-to-end latency for a typical coprocessor workload (10M–50M cycles) when comparing SP1's highly optimized continuations/recursion pipeline against RISC Zero's older Bonsai/steel architecture. SP1's "Continuations" feature splits execution into chunks, proves them in parallel, and recursively aggregates them. This turns a monolithic 100M cycle proof into a map-reduce job.

The Coprocessor Mental Model

A ZK Coprocessor moves heavy computation off-chain (SP1) and verifies the result on-chain (Solidity Verifier).

  1. Host (Off-chain): Executes Rust code → Generates Execution Trace → Proves via SP1 Core (STARK) → Compresses via SP1 Recursion (STARK) → Wraps via SP1 Groth16 (SNARK).
  2. Contract (On-chain): Verifies Groth16 Proof (280k gas) → Reads Public Values (Output) → Executes Business Logic.

2. The Circuit: Fibonacci 10M Cycles

We start with a canonical "heavy compute" task: Calculating the 4,782nd Fibonacci number (approx 10M RISC-V cycles). This simulates a real coprocessor workload (e.g., ML inference, order book simulation, ZK-ML).

Prerequisites 

# 1. Install Rust & SP1 Toolchain
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
source "$HOME/.cargo/env"
cargo install cargo-prove # SP1 CLI wrapper

# 2. Install SP1 Toolchain (Downloads ~2GB prover binaries)
cargo prove install-toolchain

# 3. Verify
sp1 --version
# sp1 3.0.0
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Project Structure 

zk-coprocessor/
├── program/          # The Guest Code (Runs inside ZK-VM)
│   ├── src/
│   │   └── main.rs
│   └── Cargo.toml
├── script/           # Host Code (Drives Proving)
│   ├── src/
│   │   └── main.rs
│   └── Cargo.toml
├── contracts/        # Solidity Verifier & App
│   ├── src/
│   │   ├── FibonacciVerifier.sol
│   │   └── ZKPriceOracle.sol
│   ├── script/
│   │   └── Deploy.s.sol
│   └── foundry.toml
└── Cargo.toml        # Workspace root
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program/Cargo.toml 

[package]
name = "fibonacci-program"
version = "0.1.0"
edition = "2021"

[dependencies]
sp1-sdk = { version = "3.0.0", features = ["execute"] }
# No std library inside the VM!
# We use `sp1-lib` which provides `println`, `hash`, `verify` syscalls.
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program/src/main.rs — The Guest Code 

// program/src/main.rs
#![no_main]
#![no_std]

use sp1_derive::AlignedBorrow;
use sp1_lib::syscalls::syscall_write;

// We use the SP1 standard library entry point macro
sp1_zkvm::entrypoint!(main);

pub fn main() {
    // 1. Read Inputs from Public Values (stdin equivalent)
    // In a real app, this comes from the Host via `stdin.write(&n)`
    let n: u64 = sp1_zkvm::io::read();

    // 2. Heavy Computation: Iterative Fibonacci (avoids stack overflow)
    // Target: n = 4,782,000 approx 10M cycles
    let mut a: u128 = 0;
    let mut b: u128 = 1;

    // We use u128 to prevent overflow for large n, though we only commit the last 4 bytes
    for _ in 0..n {
        let c = a.wrapping_add(b);
        a = b;
        b = c;
    }

    // 3. Commit Result to Public Values (stdout equivalent)
    // The Verifier contract reads these exact bytes in order.
    sp1_zkvm::io::commit(&n);      // Echo input for binding
    sp1_zkvm::io::commit(&a);      // Result (F_n)
    sp1_zkvm::io::commit(&b);      // Result (F_{n+1})
}
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Key Concept: sp1_zkvm::io::read() and commit() are syscalls (syscall_read / syscall_write). They interact with the Public Values stream. The Verifier must read them in the exact same order.

script/Cargo.toml — The Host (Prover) 

[package]
name = "fibonacci-host"
version = "0.1.0"
edition = "2021"

[dependencies]
sp1-sdk = { version = "3.0.0", features = ["network-prover", "groth16"] }
anyhow = "1.0"
clap = { version = "4.4", features = ["derive"] }
tokio = { version = "1.34", features = ["full"] }
# For deploying to Arbitrum
ethers = { version = "2.0", features = ["abigen"] }
dotenvy = "0.15"
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script/src/main.rs — Proving & Verification Flow

This is where the magic happens: Local Execution -> SP1 Network Proving -> Groth16 Wrapper -> On-chain Verification.

// script/src/main.rs
use sp1_sdk::{include_elf, HashableKey, ProverClient, SP1Stdin, SP1ProofMode};
use ethers::{prelude::*, utils::keccak256};
use std::sync::Arc;
use anyhow::Result;

// 1. Embed the compiled Guest ELF binary
// This path is relative to the workspace root where `cargo prove build` outputs artifacts.
const ELF: &[u8] = include_elf!("fibonacci-program");

#[tokio::main]
async fn main() -> Result<()> {
    // --- CONFIG ---
    let n: u64 = 4_782_000; // ~10M Cycles
    let rpc_url = std::env::var("ARBITRUM_RPC_URL")?;
    let private_key = std::env::var("PRIVATE_KEY")?;

    // --- 1. SETUP SP1 CLIENT ---
    // ProverClient handles the heavy lifting: Core -> Recursion -> Groth16
    let client = ProverClient::from_env(); // Reads SP1_PROVER env var (local/network)

    // --- 2. EXECUTE (Optional: Dry run to get cycle count) ---
    println!("🚀 Executing locally to estimate cycles...");
    let (_, report) = client.execute(ELF, &SP1Stdin::new().write(&n)).run().unwrap();
    println!("✅ Cycles used: {}", report.total_instruction_count());
    // Expected: ~10,000,000

    // --- 3. PROVE (GROTH16 MODE) ---
    // This is the production path. 
    // Mode::Groth16 triggers: Core STARK -> Recursive STARK -> Groth16 Wrapper.
    println!("⏳ Proving via SP1 Network (Groth16)... This takes ~2.3s network time.");
    let stdin = SP1Stdin::new().write(&n);

    // SP1_PROVER=network uses Succinct's hosted prover cluster (Centralized - see Gotchas)
    // SP1_PROVER=local uses your machine (Requires 64GB RAM)
    let proof = client.prove(&stdin, ELF, SP1ProofMode::Groth16).plonk().run().unwrap();

    println!("✅ Proof Generated!");
    println!("   Proof Size: {} bytes", proof.bytes().len()); // ~47KB STARK -> ~2KB Groth16
    println!("   Verification Key Hash: {}", client.vk_hash(ELF).to_string());

    // --- 4. PARSE PUBLIC VALUES (For Solidity Calldata) ---
    // The Groth16 proof contains the public values embedded.
    // We need to extract them to pass to the Solidity verifier.
    let public_values = proof.public_values;
    let mut pv_stream = public_values.as_slice();

    // Read back exactly as committed in Guest: n, a, b
    let proven_n = u64::from_le_bytes(pv_stream[0..8].try_into().unwrap());
    let fib_n = u128::from_le_bytes(pv_stream[8..24].try_into().unwrap());

    println!("📊 Public Values:");
    println!("   n: {}", proven_n);
    println!("   F_n (truncated): {}", fib_n); // u128 is 16 bytes

    // --- 5. ON-CHAIN VERIFICATION (Foundry Cast / Ethers) ---
    // We construct the calldata for the Verifier Contract manually here
    // to show the exact ABI encoding.

    // Verifier ABI: verifyProof(bytes proof, bytes pubInputs, bytes32 vkHash)
    // Note: SP1 Groth16 verifier expects (proof, public_inputs, vk_hash)

    let vk_hash = client.vk_hash(ELF); // [u8; 32]
    let proof_bytes = proof.bytes();   // The raw Groth16 proof bytes (Pi_a, Pi_b, Pi_c)

    // Encode Public Inputs for Solidity: 
    // Solidity expects the public inputs as a flat byte array matching the circuit's public signals.
    // SP1 Groth16 circuit public signals = [vk_hash, committed_values_digest...]
    // BUT the generated Solidity Verifier (via `cargo prove build-verifier`) 
    // expects the *raw committed values* as `publicValues` argument.

    // Let's use the SDK helper to get the exact calldata for the generated verifier.
    let verifier_calldata = proof.encode_verifier_input(ELF)?;

    println!("📦 Calldata length: {} bytes", verifier_calldata.len());

    // --- 6. DEPLOY / CALL VIA ETHERS (Optional Live Demo) ---
    // See Section 3 for the Solidity Verifier deployment.
    // Here we just print the data needed for `cast send`.

    println!("\n🎯 DEPLOYMENT DATA:");
    println!("VK Hash (Constructor Arg): 0x{}", hex::encode(vk_hash));
    println!("Proof Calldata (verifyProof arg): 0x{}", hex::encode(&verifier_calldata));

    Ok(())
}
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Build & Prove Commands 

# 1. Build Guest Program (Compiles to RISC-V ELF)
cargo prove build --release

# 2. Run Host (Proves via Network)
# Requires SP1_PROVER=network (default) and SP1_PRIVATE_KEY for network auth
export SP1_PROVER=network
export SP1_PRIVATE_KEY=<your_succinct_network_key> # Get from https://prover.succinct.xyz
cargo run --release --manifest-path script/Cargo.toml

# 3. Local Proving (Requires 64GB RAM, 16 Cores, Metal/CPU)
export SP1_PROVER=local
cargo run --release --manifest-path script/Cargo.toml
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Expected Output (Network):

🚀 Executing locally to estimate cycles...
✅ Cycles used: 10,004,321
⏳ Proving via SP1 Network (Groth16)... This takes ~2.3s network time.
✅ Proof Generated!
   Proof Size: 2,144 bytes (Groth16)
   Verification Key Hash: 0xabc123...
📊 Public Values:
   n: 4782000
   F_n (truncated): 123456789...
📦 Calldata length: 1,204 bytes
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3. Integration: Solidity Verifier on Arbitrum

SP1 generates a Groth16 Verifier Contract tailored to your specific Program VK (Verification Key). This is not a universal verifier; it is program-specific.

Generate the Verifier Contract 

# This generates a Solidity file: `contracts/src/FibonacciVerifier.sol`
# It contains the VK hardcoded in the constructor (or immutable) and the `verifyProof` function.
cargo prove build-verifier --manifest-path program/Cargo.toml --output-dir contracts/src
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contracts/src/FibonacciVerifier.sol (Generated ~247 Lines)

Do not write this manually. The generated code handles the complex Pairing checks and public input hashing. Below is a simplified representation of the critical parts.


solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

// Generated by SP1 SDK. 
// Uses `solmate` or `gnark` style pairing library (BN254 precompiles: 0x06, 0x07, 0x08).
import "forge-std/console.sol";
import "./lib/Pairing.sol"; // Standard BN254 Pairing Library

contract FibonacciVerifier {
    using Pairing for *;

    // --- VK HARDCODED / IMMUTABLE ---
    // These are generated specific to your ELF binary.
    // vkHash = keccak256(abi.encode(vk_g1, vk_g2, vk_gamma, vk_delta, vk_ic))
    bytes32 public immutable vkHash;

    // Verifying Key Components (G1/G2 Points)
    // Stored as immutable to save deployment gas.
    Pairing.G1Point public immutable vk_g1_alpha;
    Pairing.G2Point public immutable vk_g2_beta;
    Pairing.G1Point public immutable vk_g1_gamma;
    Pairing.G1Point public immutable vk_g1_delta;
    Pairing.G1Point[] public immutable vk_ic; // IC = Instance Commitment (Public Inputs Coeffs)

    constructor() {
        // VK VALUES INJECTED BY `cargo prove build-verifier`
        // Example values (truncated):
        vkHash = 0x1234...;
        vk_g1_alpha = Pairing.G1Point(0x..., 0x...);
        vk_g2_beta = Pairing.G2Point(0x..., 0x...);
        vk_g1_gamma = Pairing.G1Point(0x..., 0x...);
        vk_g1_delta = Pairing.G1Point(0x..., 0x...);
        vk_ic = [Pairing.G1Point(0x..., 0x...), ...]; // Length = num_public_inputs + 1
    }

    // --- MAIN ENTRY POINT ---
    // Called by your Application Contract (e.g., ZKPriceOracle)
    // proof: Raw Groth16 bytes (Pi_a || Pi_b || Pi_c) ~ 25

#SP1 #ZK #Succinct #Arbitrum
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