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

# Sign Voucher

> Sign a voucher with a public key.

`POST /api/v1/vouchers/:voucherId/sign-voucher`

Attaches a cryptographic signature to a voucher. This is used for protocols that require an explicit signing step separate from resolution.

## Parameters

### Path

| Name        | Type     | Required | Description            |
| ----------- | -------- | -------- | ---------------------- |
| `voucherId` | `string` | Yes      | The voucher ID to sign |

### Body

| Name        | Type     | Required | Description                                   |
| ----------- | -------- | -------- | --------------------------------------------- |
| `publicKey` | `string` | Yes      | Public key used for signing, 1–256 characters |
| `signature` | `string` | Yes      | Cryptographic signature, 1–256 characters     |

## Request example

```shell theme={null}
curl --request POST 'https://payments.bleepay.com/api/v1/vouchers/vch_482916/sign-voucher' \
  --header 'Authorization: Bearer <payer_token>' \
  --header 'Content-Type: application/json' \
  --data '{
    "publicKey": "0xPublicKey...",
    "signature": "0xSignature..."
  }'
```

## Response

### Response schema

Returns the updated voucher object with the signature attached.

### Error responses

| Status | Code                | Description                     |
| ------ | ------------------- | ------------------------------- |
| `400`  | `validation_failed` | Invalid or missing fields       |
| `401`  | `unauthorized`      | Missing or invalid bearer token |
| `404`  | `not_found`         | Voucher not found               |