Cronozen Proof

Tamper-proof audit trail for AI decisions. Record, verify, and export cryptographic proof chains — via MCP, SDK, or REST API.

Every AI decision is chained via SHA-256, verifiable by anyone, and exportable as JSON-LD for audit compliance.

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Why Cronozen Proof?

AI agents are making real decisions in production — approvals, classifications, workflow executions. But when something goes wrong, can you prove what happened?

Cronozen Proof gives you:

• Immutable hash chain — SHA-256 linked records that can't be tampered with
• Public verification — Anyone can verify a proof without authentication
• Audit-ready export — JSON-LD v2.0 evidence documents
• 3 integration paths — MCP Server, Node SDK, REST API

Built for compliance

• EU AI Act — Human oversight & auditability requirements
• Korea AI Basic Act (2026) — AI decision documentation mandates
• SOC 2 — Audit trail evidence generation

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Quick Start

Option 1: npm SDK (Recommended)

npm install cronozen

import { Cronozen } from 'cronozen';

const client = new Cronozen({ apiKey: 'your-api-key' });

// Record an AI decision
const decision = await client.decisions.record({
  domain: 'loan-approval',
  purpose: 'AI evaluated credit risk for application #1234',
  finalAction: 'Approved with conditions',
  evidenceLevel: 'AUDIT_READY',
});

// Verify integrity
const verification = await client.decisions.verify(decision.id);
console.log(verification.integrity.hash_valid); // true

Option 2: MCP Server (for AI clients)

Connect Claude Desktop, Cursor, or any MCP-compatible client:

{
  "mcpServers": {
    "cronozen-proof": {
      "url": "https://mcp.cronozen.com/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_API_KEY"
      }
    }
  }
}

Or install via Smithery:

smithery mcp add cronozen/proof

Available MCP Tools:

Tool	Description
proof_record	Record an AI decision with SHA-256 hash chain
proof_verify	Verify a proof record's cryptographic integrity
proof_chain_verify	Verify an entire domain's hash chain
proof_get	Retrieve a proof with full details
proof_export_jsonld	Export as JSON-LD v2.0 evidence document
proof_public_verify	Public verification (no auth required)

Option 3: DPU Core (Self-hosted library)

For maximum control, use the core hash chain library directly:

npm install @cronozen/dpu-core

import { computeChainHash, createDPUEnvelope } from '@cronozen/dpu-core';

// Create a hash chain link
const hash = computeChainHash(content, previousHash, timestamp);

// Create a full DPU envelope
const envelope = createDPUEnvelope({ content, previousHash, timestamp });

Zero dependencies. Pure cryptographic functions. Run anywhere.

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Packages

This monorepo contains the open-source Cronozen Proof ecosystem:

Package	npm	Description
@cronozen/dpu-core		Core hash chain engine — zero dependencies, pure crypto
@cronozen/dp-schema-public		Shared types, enums, JSON-LD schema definitions
cronozen		High-level SDK — decision.record() / decision.verify()
@cronozen/mcp-server	—	MCP Server for AI client integration

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Architecture

Your Application / AI Agent
    │
    ├─── cronozen SDK ──────► Cronozen Cloud API
    │    (npm install cronozen)     │
    │                               ▼
    ├─── MCP Server ────────► Decision Proof Store
    │    (Streamable HTTP)          │
    │                               ▼
    └─── @cronozen/dpu-core ─► SHA-256 Hash Chain
         (self-hosted)         │
                               ▼
                          Tamper-proof Evidence
                          (JSON-LD v2.0 export)

Hash Chain: Every decision record contains a SHA-256 hash computed from its content + the previous record's hash + timestamp. This creates an append-only chain — tampering with any record breaks the chain for all subsequent records.

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Self-Hosted Deployment

Docker

cd mcp-server
docker build -t cronozen-mcp .
docker run -p 3100:3100 \
  -e CRONOZEN_API_URL=https://mcp.cronozen.com \
  -e CRONOZEN_API_TOKEN=your-token \
  cronozen-mcp

From Source

git clone https://github.com/cronozen/proof.git
cd proof/mcp-server
npm install
cp .env.example .env  # Configure your API endpoint
npm run dev

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Cronozen Cloud

Don't want to self-host? Cronozen Cloud handles hosting, security, backups, and updates for you.

	Self-Hosted	Cloud Pro	Cloud Business	Enterprise
Price	Free	$99/mo	$299/mo	Custom
Events	Unlimited	1,000/mo	Unlimited	Unlimited
Source Code	Full access	—	—	—
Support	Community	Email	Priority	Dedicated
SSO	—	—	✓	✓
SLA	—	—	99.9%	Custom
On-premise	✓ (DIY)	—	—	✓ (Managed)

View pricing →

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How It Works

1. Record — Your app sends a decision event (domain, purpose, action, evidence level)
2. Chain — The event is hashed with SHA-256, linked to the previous record
3. Verify — Anyone can verify a single record or the entire chain
4. Export — Generate JSON-LD v2.0 evidence documents for auditors

Genesis ──► Record #1 ──► Record #2 ──► Record #3
  │            │              │              │
  hash₀       hash₁          hash₂          hash₃
               │              │              │
          SHA-256(         SHA-256(      SHA-256(
            content₁,       content₂,     content₃,
            hash₀,          hash₁,        hash₂,
            timestamp₁)     timestamp₂)   timestamp₃)

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Use Cases

• AI Agent Audit Trail — Track every decision an AI agent makes in production
• Compliance Documentation — Auto-generate tamper-proof evidence for SOC2, EU AI Act, Korea AI Basic Act
• Decision Provenance — Answer "why did the AI do this?" with cryptographic proof
• Human-in-the-Loop Evidence — Record human approval/rejection alongside AI decisions
• Settlement Proof — Immutable records for financial transactions and approvals

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Contributing

We welcome contributions! See CONTRIBUTING.md for guidelines.

git clone https://github.com/cronozen/proof.git
cd mcp-server
npm install
npm run build

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License

Apache-2.0 — See LICENSE for details.

Cronozen Proof Enterprise (governance, compliance engine, advanced chain verification) is available under a commercial license. Contact us →

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<p align="center"> <a href="https://cronozen.com/proof">cronozen.com/proof</a> · <a href="https://smithery.ai/servers/cronozen/proof">Smithery</a> · <a href="https://www.npmjs.com/package/cronozen">npm</a> </p>