circuits

PDF Verification Circuits

Zero-knowledge circuits for PDF text extraction and digital signature verification using SP1. Generates cryptographic proofs that specific text appears in signed PDF documents.

🎯 Overview

This project provides SP1 circuits that can:

• Extract text from PDF documents
• Verify digital signatures
• Prove that specific text appears at exact positions
• Generate cryptographic proofs for blockchain verification

🚀 Quick Start

Installation

Add to your Cargo.toml:

[dependencies]
zkpdf-lib = { git = "https://github.com/privacy-ethereum/zkpdf", branch = "main", subdir = "circuits/lib" }

📚 For complete API documentation, see Circuit Library Documentation

Requirements

• Rust
• SP1

Basic Usage

use zkpdf_lib::{verify_pdf_claim, PDFCircuitInput};

// Create input for PDF verification
let input = PDFCircuitInput {
    pdf_bytes: pdf_data,
    page_number: 0,
    offset: 100,
    substring: "Important Document".to_string(),
};

// Verify PDF and generate proof
let result = verify_pdf_claim(input)?;

🔧 Running the Circuits

Execute the Program

To run the PDF verification without generating a proof:

cd script
cargo run --release -- --execute

Generate SP1 Core Proof

To generate a core proof for PDF verification:

cd script
cargo run --release -- --prove

Generate EVM-Compatible Proof

Warning

Requires at least 16GB RAM for Groth16/PLONK proofs.

# Groth16 proof
cd script
cargo run --release --bin evm -- --system groth16

# PLONK proof
cd script
cargo run --release --bin evm -- --system plonk

Prover Server

Run the HTTP API server for remote PDF verification:

# Set environment variables
export SP1_PROVER=network
export NETWORK_PRIVATE_KEY=0x...

# Run the server
cd script
cargo run --release --bin prover

API Endpoints:

• POST /prove - Generate PDF verification proof
• POST /verify - Verify an existing proof

Example Request:

{
  "pdf_bytes": [
    /* PDF file bytes */
  ],
  "page_number": 0,
  "sub_string": "Important Document",
  "offset": 100
}

Retrieve Verification Key

cd script
cargo run --release --bin vkey

🧪 Testing

# Run all tests
cargo test

# Run specific circuit tests
cargo test -p zkpdf-lib

🌐 Smart Contract Integration

The generated proofs can be verified on-chain using the provided Solidity contracts:

contract PdfVerifier {
    function verifyPdfProof(
        bytes calldata proof,
        bytes32 messageDigestHash,
        bytes32 signerKeyHash,
        bytes32 substringHash,
        bytes32 nullifier
    ) external view returns (bool);
}

📚 Dependencies

• sp1-sdk – SP1 zero-knowledge framework
• pdf-utils – PDF processing libraries
• alloy-primitives – Cryptographic primitives
• serde – Serialization framework

📄 License

This project is licensed under the same terms as the parent repository.