TruChain – AI Content Authenticity Verification on Blockchain

🔭 Overview

TruChain is a decentralized platform for verifying the authenticity of AI-generated content. It combines GPT-4o-powered analysis with on-chain proof storage — if GPT determines an image or piece of content is AI-generated, that verification result is permanently recorded on the blockchain via a smart contract, creating a tamper-proof authenticity record.

❓ The Problem

As AI-generated content (images, text, deepfakes) becomes indistinguishable from real content, there's a growing need for verifiable authenticity checks. Traditional watermarking fails silently. TruChain solves this with a two-layer approach: AI-powered detection via GPT-4o, plus immutable on-chain proof that the check occurred and what the result was.

🛠️ Architecture

NestJS API (Port 3000)
├── Inference Module   → GPT-4o API for image/content analysis
├── Blockchain Module  → ethers.js smart contract interaction
├── Verification Module → Orchestrates: analyze → hash → store on-chain
└── Shared Module      → Config, logging, trace IDs
         │                       │
         ▼                       ▼
Smart Contracts (Solidity)    TruChain ERC-20 Token
├── ImageVerification.sol     ├── Payment for verification
│   └── On-chain proof store  ├── Staking mechanism
└── Content hash verification └── Burn mechanics

🛠️ What I Built

🤖 AI Inference Layer

🤖 OpenAI GPT-4o integration for multi-modal content analysis (image + text)
🖼️ Base64 image processing pipeline for direct upload verification
📊 Confidence scoring for AI-generated content detection
📋 Structured verification results with detailed reasoning

⛓️ Blockchain Proof Storage

📜 ImageVerification.sol: stores verification results on-chain — content hash, AI confidence score, verification timestamp, verifier address
🪙 TruChain.sol: ERC-20 token for the verification payment system — users pay TruChain tokens to verify content, with staking and burn mechanics
🔐 Verifier authorization system — only approved verifiers can submit on-chain proofs

⚙️ NestJS Backend

🔗 Unified API orchestrating the full flow: content submission → GPT analysis → hash generation → on-chain storage → result return
📋 Structured logging with trace IDs for every request
🏥 Health check endpoints for API and blockchain connection monitoring
🐳 Docker-ready with docker-compose for local development

🧪 Testing Infrastructure

🧪 Jest + Supertest end-to-end test suite
🖼️ Base64 image verification tests
📜 Contract interaction tests
🔧 Utility scripts for blockchain troubleshooting and contract setup

⭐ Key Highlights

🔗 Full AI + blockchain integration: GPT-4o inference results stored as immutable on-chain proofs
🪙 ERC-20 token economics: payment, staking, and burn mechanics for sustainable verification ecosystem
🏗️ Production-grade NestJS architecture with modular design and structured observability
📜 Smart contract suite covering verification storage, token payments, and verifier authorization

🛡️ TruChain – AI Content Authenticity Verification on Blockchain

Stack