Portfolio
Production systems I've designed and built. Each one runs on private blockchain infrastructure with immutable records, cryptographic verification, and full audit trails.
ChainVault
Tamper-proof deal room with wire fraud prevention
A full-stack platform for real estate closings and M&A transactions. Documents are encrypted client-side before upload — the server never sees plaintext. Every action is recorded on a private 4-node blockchain with BFT consensus.
Technical Stack
- Blockchain: 4-node Antelope chain with BFT finality (tolerates 1 node failure)
- Smart Contracts: 3 C++ contracts (chainvault, auditlog, wirevault) — separated so audit survives upgrades
- Indexing: Hyperion full-history API + custom sync daemon materializing to PostgreSQL
- Document Storage: MinIO (S3-compatible) with AES-256-GCM client-side encryption
- Frontend: Next.js 15, App Router, TypeScript, Tailwind v4
- Auth: SSO-ready (Google, Microsoft Entra), multi-tenant membership
- Billing: Stripe integration with usage-based plans
Key Features
- Wire transfer verification — multi-party on-chain confirmation before funds move
- Encrypted document vault with blockchain content hash commitments
- Full audit trail — every action immutably recorded
- Multi-tenant with role-based access control
- Blockchain explorer and superadmin panel
Live at: chainvault.amiheines.com
Verarta
Art provenance and authentication on private blockchain
A provenance tracking system for art and collectibles. Each piece gets a verifiable chain of ownership recorded on a private blockchain. Certificates of authenticity are cryptographically signed and permanently linked to the artwork's on-chain record.
What It Demonstrates
- Provenance tracking with cryptographic proof of ownership transitions
- Tamper-proof certificates of authenticity
- Private blockchain running on the same infrastructure pattern as ChainVault
- The versatility of the same core technology across different domains
Live at: verarta.com
Self-Hosted Infrastructure
Production-grade stack running on bare metal
Every project above runs on infrastructure I built and manage:
- 4 block producers with BFT consensus — 3/4 needed for finality, tolerates 1 failure
- State History Plugin (SHIP) node for full blockchain state streaming
- Hyperion full-history indexer backed by Elasticsearch
- PostgreSQL as a disposable read cache — can be rebuilt from chain at any time
- MinIO for S3-compatible encrypted blob storage
- nginx reverse proxy with rate limiting, SSL via Let's Encrypt
- systemd services with security hardening (NoNewPrivileges, ProtectSystem)
All ports bind to localhost only — nginx is the sole external entry point. Docker containers use named volumes with JSON logging rotation.