Digital Garbage Record Book: How Modern Vessels Can Meet MARPOL Annex V

What dGRB v2 Does

dGRB v2 is a fully offline-capable Digital Garbage Record Book that runs entirely in the browser of any device on the vessel — tablet, bridge workstation, or officer’s laptop. No server connectivity required to create, sign, or store entries. When connectivity is available, data syncs to a shore-based server for fleet management and regulatory oversight.

Cryptographic Signing & Hash Chain Integrity

Every entry is signed with the officer’s PIN using HMAC-SHA256 before being written to the record. Each entry also extends a SHA-256 hash chain — every new entry includes a hash of the previous entry’s data, creating an immutable, tamper-evident chain. If someone alters a past entry, the hash chain breaks and the tampering is detectable.

This is not just compliance theater. It’s the same cryptographic technique used in financial ledgers and supply chain logging — and it works entirely offline, with no blockchain needed.

Real-Time MARPOL Compliance Checking

Before an officer signs off on an entry, dGRB v2 runs a compliance check against the current position, garbage category, disposal method, and applicable special area rules. It evaluates:

• Distance from shore — different categories require different minimum distances (3nm, 12nm, etc.)
• Special areas — Mediterranean, Baltic, North Sea, Red Sea, Persian Gulf, Antarctic, and Arctic all have additional restrictions
• Particle size requirements — ground food waste must be ≤25mm to discharge between 3–12nm from shore
• HME cargo classification — Hazardous and Noxious Substances cargo residues require specific handling
• Flag state configuration — vessels can configure their flag state’s specific MARPOL discharge rules

If a discharge would be illegal, the officer sees a clear violation message before signing. The compliance result is stored with the entry.

Offline-First Architecture

The entire application — including the compliance engine, cryptographic functions, and database — runs client-side in the browser using WebAssembly and IndexedDB. An entry created at 400 nautical miles from the nearest server is identical in integrity and cryptographic validity to one created in port with a fiber connection.

Sync to the shore server is opportunistic: when connectivity is available, entries are pushed up with their full hash chain and audit trail. Shore-based environmental officers and fleet managers can review fleet-wide compliance, identify gaps, and monitor sync status.

Role-Based Access Control

Three roles with distinct permissions:

The auth system is token-based with httpOnly JWT cookies, meaning credentials are never stored in browser localStorage where they’d be vulnerable to XSS. Officers log in once per session; the token persists across page refreshes.

The Human Factors

Every digital compliance tool competes with the fundamental truth that crew are busy and forms are annoying. dGRB v2 was designed around this reality.

Entry wizard, not blank form. The 7-step entry flow — Vessel → Category → Amount → Position → Method → Review → Sign-off — guides the officer through exactly what the record requires. There’s no ambiguity about what fields are mandatory or in what format coordinates should be entered.

GPS auto-capture. The position step can auto-capture from the device’s GPS with a single button press. Manual coordinate entry is also available. The compliance engine immediately evaluates the position against the selected category and disposal method.

PIN-based signing. No wet ink, no countersignature, no witness. The officer enters their PIN, the entry is cryptographically signed with their identity bound to the record. The PIN is salted and hashed — not stored in plaintext anywhere.

Clear compliance feedback. Before signing, officers see a plain-language compliance result: “All compliance checks passed” or a specific list of violations with distance and particle size requirements. This isn’t just record-keeping — it’s crew education in real time.