LensMint Camera

LensMint is a full hardware-to-blockchain camera system designed to guarantee the authenticity and ownership of real-world photos. Built on a Raspberry Pi camera with hardware-derived cryptographic identity, every photo is signed at capture, hashed, and proven genuine using zero-knowledge proofs generated through vlayer and verified on-chain via RISC Zero. The system uploads all media to Filecoin for permanent decentralized storage and mints an ERC-1155 NFT representing the authenticated memory. A built-in QR system lets people in the photo instantly claim their NFT, enabling proof of attendance, verified memories, and automatic revenue sharing. LensMint provides a trustless way to prove a photo’s device origin, timestamp, and integrity—solving authenticity, provenance, and monetization issues for creators, journalists, events, and scientific documentation.

📌 Problem

Modern photography has lost trust. AI-generated images, deepfakes, and easy metadata manipulation make it nearly impossible to verify whether a photo is real, who captured it, or whether it has been tampered with. Journalists, wildlife photographers, event organizers, and creators need a reliable way to prove authenticity. Creators also lack transparent monetization; there’s no standard for proving ownership, tracking usage, or distributing royalties.

💡 Solution

LensMint is a hardware-based Web3 camera system that creates tamper-proof, cryptographically verified photos at the moment of capture. Each photo is automatically signed, hashed, verified with zero-knowledge proofs, stored permanently, and converted into a claimable NFT. People in the photo simply scan a QR code to claim their authenticated memory, enabling verified attendance and frictionless creator monetization.

🛠️ How It Works (Technical Breakdown)

Each camera generates a hardware-derived cryptographic identity tied to the device.

When a photo is taken, the image is signed using the device key and its SHA-256 hash is generated.

This data is passed to vlayer to generate a zero-knowledge proof proving the device, timestamp, and integrity—without exposing raw metadata.

A RISC Zero verifier contract validates the ZK proof entirely on-chain.

Image + metadata are stored permanently on Filecoin with immutable CIDs.

The camera displays a QR code linked to a claim server; users scan and enter their wallet to receive the minted NFT.

Smart contracts ensure provenance, authenticity, and optional revenue-sharing between tagged participants.

🎯 What LensMint Enables

Trustless, verifiable photography (proof that a real device captured a real moment)

Proof of attendance for events, meetups, conferences

On-chain memory preservation with permanent Filecoin storage

Verified journalism and scientific documentation

Creator monetization via royalties and transparent provenance

ZK-powered privacy, proving authenticity without leaking sensitive info like exact GPS or EXIF

🔧 Hardware Layer

LensMint runs on a Raspberry Pi 4 with a Pi Camera Module v3 and a 3.5" touchscreen. We built a custom hardware identity system where the device generates a private key derived from hardware entropy (serial, CPU ID, randomness mix). This creates a unique, non-exportable camera identity used to sign every photo.

The camera interface uses Picamera2, with real-time preview, 1080p capture, rotation correction, and custom Kivy UI for a touch-friendly camera app.

We also wrote low-level image handling utilities to:

• Capture RAW JPEG buffers
• Compute SHA-256 on-device
• Sign image metadata with hardware key
• Queue offline uploads when network is down

This makes the camera act like a standalone cryptographic signer for all photos.

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🖥️ Software (On-Device Application)

The frontend is a Python/Kivy app providing:

• Live preview
• Capture & video mode
• Gallery
• QR claiming interface
• Status feedback

It communicates with the backend via a lightweight local REST API.

A small Python module handles:

• Hardware key generation
• Signing operations
• Image hashing
• EXIF sanitization
• Automatic device registration via Web3

This turns the camera into a self-contained cryptographic photo oracle.

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🌐 Hardware Web3 Service (Backend)

The backend is a Node.js/Express service running on the same Pi (or edge server). It handles everything the camera shouldn’t: heavy Web3 calls, uploads, and ZK integration.

Tech stack:

• Node.js (Express) – local REST API
• Ethers.js – blockchain interaction
• SQLite – claims database
• Multer – file handler
• Synapse Filecoin SDK – uploads to Filecoin/IPFS

This service receives signed images, verifies signatures, uploads media, and triggers mints.

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🧠 Zero-Knowledge Proof Pipeline (vlayer + RISC Zero)

This is the core innovation.

1. Generating ZK Proofs (vlayer API) We use vlayer to produce zero-knowledge proofs from external metadata and device signatures.

It proves:

• The photo hash matches
• The device key matches a registered identity
• Timestamp is fresh
• Image wasn’t AI-generated or altered

This allows on-chain verification without revealing EXIF or sensitive data.

2. On-chain verification (RISC Zero Verifier Contract) The ZK proof is validated using a RISC Zero verifier contract, allowing trustless validation of:

• Authentic capture
• Device identity
• Integrity of metadata

This is the cornerstone of tamper-proof photography.

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📦 Storage Layer (Filecoin / IPFS)

The Synapse SDK uploads:

• Raw photo file
• Metadata JSON (proof, signatures, CIDs, device ID, hash)

Both are stored permanently on Filecoin with CID-based addressing.

This gives us:

• Permanent, decentralized memory
• Immutable provenance
• Zero dependency on centralized cloud storage

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🔗 Smart Contracts (Ethereum Sepolia)

Three key contracts:

1. DeviceRegistry.sol

• Registers camera identities
• Ensures only authorized devices can mint
• Verifies device → wallet ownership

2. LensMintERC1155.sol

• Mints the actual authenticated photo NFTs
• Enforces device-only minting
• Supports editions, transfers, and claims

3. LensMintVerifier.sol

• Uses RISC Zero to verify ZK proofs
• Validates image hash + metadata hash
• Confirms the device is legit

All logic is optimized for gas and tamper-proof provenance.

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📱 Claiming System (Public Server + QR Flow)

We built a public claim server where each photo:

• Creates a unique claim ID
• Generates a QR code
• Waits for user wallet submission
• Signals the device to mint to that wallet

This allows users in the photo to instantly claim the NFT without needing the camera operator.

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⚙️ Hacky (but awesome) Engineering

We had to build several creative hacks:

• Hardware-derived private key generator without exposing entropy sources
• Custom Python → Node communication layer to handle signed JPEG buffers
• On-device queue-based uploader for bad network situations
• Real-time QR code generation inside a Kivy UI
• Image signing + hashing pipeline optimized to avoid lag on Raspberry Pi
• A mini Web3 RPC load balancer to avoid slow public RPCs
• A single-click “auto-register device on-chain” system

These hacks allowed a low-powered Raspberry Pi to run ZK proofs, Filecoin uploads, cryptographic signing, and real-time camera preview all together.