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TruChain – AI Content Authenticity Verification on Blockchain

Decentralized platform for verifying AI-generated content authenticity using GPT-4o inference and immutable on-chain proof storage. NestJS backend orchestrates AI analysis, blockchain verification, and an ERC-20 token payment system.

Full-Stack AI / Blockchain Engineer2025
GitHub

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NestJSTypeScriptOpenAI GPT-4oSolidityHardhatethers.jsPostgreSQLDockerJest

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 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

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 a sustainable verification ecosystem
  • Production-grade NestJS architecture with modular design and structured observability
  • Smart contract suite covering verification storage, token payments, and verifier authorization