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

# Substrate (Polkadot)

> Reference for the Substrate signing endpoint, including supported signature kinds, request payloads, and the fields required to sign Substrate transactions.

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` |

### Hex String

```json theme={null}
{
  "network": "Polymesh",
  "kind": "SignerPayload",
  "payload": "0x0403007f87d29a4746b8e59e347c0598ad811a10c3cd8735d49cf96b75973864c8c98b0475000400386d0f0019000000e143f23803ac50e8f6f8e62695d1ce9e4e1d68aa36c1cd2cfd15340213f3423eb3b9c09f232a12c50f40e023a01f0b86d679b84748cc289534d96861ef611c67"
}
```

#### Typescript Example with polkadot\{.js}

First install the polkadot\{.js} SDK. You can find the full documentation here: [https://polkadot.js.org/docs/](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 theme={null}
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 theme={null}
{
  "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": []
  }
}
```