# Substrate (Polkadot)

Substrate based chains like Polkadot, Kusama and Polymesh support the following signature `kinds`:

* `SignerPayload`, serialized [generic signer payload](https://github.com/polkadot-js/api/blob/v15.0.1/packages/types/src/extrinsic/SignerPayload.ts#L47-L51).

## SignerPayload

Signs a generic signer payload. Note: converting the generic signer payload to a signable extrinsic requires fetching metadata from the targeted blockchain. Therefore it's tied to a specific `network` rather than the blockchain kind.

| Field     | Description                                                                                      | Type - Optional                                                                                   |
| --------- | ------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------- |
| `network` | A supported Substrate network.                                                                   | String                                                                                            |
| `kind`    | `SignerPayload`                                                                                  | String                                                                                            |
| `payload` | The unsigned signer payload formatted as JSON or a serialized hex-encoded buffer as shown below. | String or [SignerPayloadJson](/d/api-docs/keys/generate-signature/substrate.md#signerpayloadjson) |

### Hex String

<pre class="language-json"><code class="lang-json"><strong>{
</strong><strong>  "network": "Polymesh",
</strong>  "kind": "SignerPayload",
  "payload": "0x0403007f87d29a4746b8e59e347c0598ad811a10c3cd8735d49cf96b75973864c8c98b0475000400386d0f0019000000e143f23803ac50e8f6f8e62695d1ce9e4e1d68aa36c1cd2cfd15340213f3423eb3b9c09f232a12c50f40e023a01f0b86d679b84748cc289534d96861ef611c67"
}
</code></pre>

#### Typescript Example with polkadot{.js} <a href="#typescript-example" id="typescript-example"></a>

First install the polkadot{.js} SDK. You can find the full documentation here: <https://polkadot.js.org/docs/>

Here a code sample to generate a signature via [the Dfns TypeScript SDK](https://github.com/dfns/dfns-sdk-ts):

```typescript
import { ApiPromise, HttpProvider } from '@polkadot/api'
import { EXTRINSIC_VERSION } from '@polkadot/types/extrinsic/v4/Extrinsic'

const walletId = 'wa-6lbfv-9esgj-xxxxxxxxxxxxxxxx'
const wallet = await dfnsClient.wallets.getWallet({ walletId })

const httpProvider = new HttpProvider(process.env.POLKADOT_NODE_URL!)
const api = await ApiPromise.create({
  provider: httpProvider,
  signer: senderWallet,
  noInitWarn: true,
})

const transaction = api.tx.balances.transferKeepAlive('5EwvHZHrKd9WYc3LByzMZW5cmxJt9VMsfYiKg5jCJb8UBfbC', 10000)
const signerPayload: any = transaction.registry.createTypeUnsafe('SignerPayload', [
  transaction,
  { version: EXTRINSIC_VERSION },
])

const res = await dfnsClient.wallets.generateSignature({
  walletId,
  body: {
    kind: 'SignerPayload',
    message: signerPayload.toHex(),
  },
})
```

### SignerPayloadJson

Please refer to the original Polkadot definition for more details: [SignerPayloadJson](https://github.com/polkadot-js/api/blob/v16.2.2/packages/types/src/types/extrinsic.ts#L32). Note that additional fields will be rejected.

| Field                | Description                                                                              | Type - Optional      |
| -------------------- | ---------------------------------------------------------------------------------------- | -------------------- |
| `address`            | ss58-encoded address of the sending account.                                             | String               |
| `blockHash`          | The hash of the checkpoint block, hex encoded.                                           | String               |
| `blockNumber`        | The checkpoint block number, hex encoded.                                                | String               |
| `era`                | The number of blocks after the checkpoint for which a transaction is valid, hex encoded. | String               |
| `genesisHash`        | The genesis hash of the chain, hex encoded.                                              | String               |
| `metadataHash`       | The metadataHash for the CheckMetadataHash SignedExtension, hex encoded.                 | String *(optional)*  |
| `mode`               | flag indicating whether to verify the metadata hash or not.                              | Integer *(optional)* |
| `method`             | The encoded method with arguments, hex encoded.                                          | String               |
| `nonce`              | The nonce for the transaction, hex encoded.                                              | String               |
| `tip`                | The tip to increase transaction priority, hex encoded.                                   | String               |
| `version`            | The version of the extrinsic.                                                            | Integer              |
| `specVersion`        | The current spec version for the runtime, hex encoded.                                   | String               |
| `transactionVersion` | The current transaction version for the runtime, hex encoded.                            | String               |
| `signedExtensions`   | The applicable signed extensions for this runtime.                                       | Array\<String>       |

```json
{
  "network": "Polymesh",
  "kind": "SignerPayload",
  "payload": {
    "address": "5H5tTnmLUqRgvTZvTwCdBKYjKLBm2gkp7u38Q9UUdJa8m6rX",
    "blockHash": "0x2ace05e703aa50b48c0ccccfc8b424f7aab9a1e2c424ed12e45d20b1e8ffd0d6",
    "blockNumber": "0x00000000",
    "era": "0x00",
    "genesisHash": "0x2ace05e703aa50b48c0ccccfc8b424f7aab9a1e2c424ed12e45d20b1e8ffd0d6",
    "method": "0x07141f3da32e72ac6eb6cb40d9e757594363a617b2c3964a2b6ec6895c6648f48d500000",
    "nonce": "0x00000000",
    "tip": "0x00000000000000000000000000000000",
    "version": 4,
    "specVersion": "0x006adb7a",
    "transactionVersion": "0x00000007",
    "signedExtensions": []
  }
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs-legacy.dfns.co/d/api-docs/keys/generate-signature/substrate.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.