> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agentsystems.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Hash Storage

> Configure where cryptographic hashes are stored

Hash storage is where the SHA-256 hashes of your audit payloads are written. Only hashes and metadata are stored externally — raw data stays in your infrastructure.

You can use one or both options.

## Decentralized (Arweave)

Hashes are written to a public, append-only ledger. Not controlled by any single vendor.

```python theme={null}
from agentsystems_notary import ArweaveHashStorage, LocalKeySignerConfig

arweave_storage = ArweaveHashStorage(
    namespace="tenant_a1b2c3d4",  # anonymous tenant identifier
    signer=LocalKeySignerConfig(
        private_key_path="/path/to/arweave-key.pem",
    ),
    # bundler_url defaults to ArDrive Turbo
)
```

### Parameters

| Parameter     | Required | Description                                                                       |
| ------------- | -------- | --------------------------------------------------------------------------------- |
| `namespace`   | Yes      | Anonymous tenant identifier (written to public ledger — do not use company names) |
| `signer`      | Yes      | Signing configuration (see [Signers](/notary/configuration/signing))              |
| `bundler_url` | No       | Arweave bundler endpoint (defaults to ArDrive Turbo)                              |

### Verification

Verify with the open-source CLI — no account required:

```bash theme={null}
npm install -g agentsystems-verify
agentsystems-verify --logs logs.zip
```

See [Independent Verification](/notary/verification/arweave) for full documentation.

## Custodied (AgentSystems)

Hashes are written to AgentSystems' write-once compliance storage. Provides a vendor relationship for enterprise compliance and procurement.

```python theme={null}
from agentsystems_notary import CustodiedHashStorage

custodied_storage = CustodiedHashStorage(
    api_key="sk_asn_prod_...",
    slug="customer-123",
)
```

### Parameters

| Parameter | Required | Description                                               |
| --------- | -------- | --------------------------------------------------------- |
| `api_key` | Yes      | AgentSystems API key (`sk_asn_test_*` or `sk_asn_prod_*`) |
| `slug`    | Yes      | Tenant slug (human-readable identifier)                   |
| `api_url` | No       | API endpoint (defaults to production)                     |

### Get an API Key

1. Sign up at [notary.agentsystems.ai](https://notary.agentsystems.ai)
2. From the Dashboard, click **Add** under API Keys
3. Name your key and select environment
4. Copy and save the key — it's only shown once

### Verification

Verify via the [Verify UI](https://verify.agentsystems.ai) or see [Verification Guide](/notary/verification/guide).

## Using Both

You can write hashes to both Arweave and custodied storage:

```python theme={null}
notary = LangChainNotary(
    raw_payload_storage=raw_payload_storage,
    hash_storage=[
        ArweaveHashStorage(...),
        CustodiedHashStorage(...),
    ],
)
```

This provides independent verification via Arweave plus a vendor relationship via AgentSystems.