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

# Interchain accounts and Cascade

> Use Cascade storage from any IBC-connected Cosmos chain through ICS-27.

Your application does not need to run on Lumera Protocol to use Cascade. Any IBC-connected Cosmos chain can register storage actions through [Interchain Accounts (ICS-27)](https://ibc.cosmos.network/v8/apps/interchain-accounts/overview/), the IBC standard that lets one chain control an account on another.

This opens cross-chain use cases.

* A DeFi protocol on Injective can store trade receipts permanently on Cascade.
* An NFT marketplace on Osmosis can use Cascade for immutable media storage.
* A DAO on the Cosmos Hub can archive governance proposals.

## How it works

<img className="block mx-auto dark:hidden" alt="Interchain Accounts (ICA) Flow" src="https://mintcdn.com/lumeraprotocol/AZkbYSakLFkCUc8N/images/diagrams/interchain-accounts-light.svg?fit=max&auto=format&n=AZkbYSakLFkCUc8N&q=85&s=b5def8abb3f2cd86b7c81a118f54b7d2" width="900" height="368" data-path="images/diagrams/interchain-accounts-light.svg" />

<img className="mx-auto hidden dark:block" alt="Interchain Accounts (ICA) Flow" src="https://mintcdn.com/lumeraprotocol/AZkbYSakLFkCUc8N/images/diagrams/interchain-accounts-dark.svg?fit=max&auto=format&n=AZkbYSakLFkCUc8N&q=85&s=a998ac4a98bfb0cdd734b3c92256f25e" width="900" height="368" data-path="images/diagrams/interchain-accounts-dark.svg" />

The flow has six steps.

1. The controller chain submits `MsgSendTx` containing a packed `MsgRequestAction`.
2. The IBC relayer delivers the packet to Lumera, the host chain.
3. Lumera's ICA host module unpacks and executes the `MsgRequestAction`.
4. An ICA address on Lumera pays the escrow fee. It must be pre-funded.
5. The action is registered on-chain with an `action_id`.
6. The application uploads the file directly to the SN-API, the HTTP API served by SuperNodes, using the `action_id`.

## Application-level keypairs

The ICA address on Lumera has no user-held private key. The controller chain controls it. Cascade solves this with an `app_pubkey` field in `MsgRequestAction`.

* The application generates a keypair on the controller side.
* The public key is included in the action registration.
* The private key signs file uploads to the SN-API.
* This separates the control plane (IBC messages) from the data plane (file transfers).

## ICA helpers in the Go SDK

The [Go SDK](https://github.com/LumeraProtocol/sdk-go) provides helpers for ICA-based Cascade.

```go theme={null}
import "github.com/LumeraProtocol/sdk-go/client"

// Pack a MsgRequestAction for ICA submission
packedMsg := client.PackRequestForICA(msg)

// Pack a MsgApproveAction for ICA submission
packedApprove := client.PackApproveForICA(approveMsg)

// Extract action IDs from the IBC acknowledgement
actionIDs := client.ExtractRequestActionIDsFromAck(ackData)
```

Configure the SDK client for ICA.

```go theme={null}
cfg := &client.Config{
    ICAOwnerKeyName: "ica-controller-key",
    ICAOwnerHRP:     "cosmos", // Bech32 prefix of the controller chain
}
```

## The ICA client CLI

The [Lumera ICA client](https://github.com/LumeraProtocol/lumera-ica-client) provides a reference CLI.

```bash theme={null}
# Upload a file via ICA
lumera-ica-client upload --file document.pdf --controller-chain cosmos

# Check action status
lumera-ica-client action status --action-id <id>

# Download a file
lumera-ica-client download --action-id <id>
```

## Security considerations

* **Control plane isolation.** IBC messages carry only metadata and fee escrow. File data never touches the IBC channel.
* **Data plane authentication.** File uploads to the SN-API use application-level signatures, independent of the ICA address.
* **Fee pre-funding.** The ICA address must hold `ulume` before registering actions. Monitor its balance to prevent failed registrations.

## Next steps

<CardGroup cols={2}>
  <Card title="Go SDK" icon="gears" href="/sdk/go">
    Install and configure the Go SDK used for ICA flows.
  </Card>

  <Card title="Upload lifecycle" icon="upload" href="/cascade/concepts/upload-lifecycle">
    What happens after the action registers on-chain.
  </Card>

  <Card title="How Cascade works" icon="diagram-project" href="/cascade/how-cascade-works">
    The end-to-end Cascade storage model in one page.
  </Card>
</CardGroup>