# authorizationHeader

> **authorizationHeader**(`signer`, `chain`, `input`): [`Promise`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise)\<`string`\>

Defined in: [claims.ts:403](https://github.com/FilOzone/synapse-sdk/blob/5989c4b03ed2fe4cf8b1ef29efe1d4ff1ad4c7bc/packages/keysmith/src/claims.ts#L403)

The `Authorization` header for one gated request: a request for `pieceCid` signed by the chain's final bearer,
presented with its chain. Make a fresh one per fetch; it expires `expiresIn` seconds after `now` (default 240).

## Parameters

| Parameter | Type |
| ------ | ------ |
| `signer` | [`ClaimSigner`](/reference/filoz/keysmith/interfaces/claimsigner/) |
| `chain` | [`ClaimChain`](/reference/filoz/keysmith/interfaces/claimchain/) |
| `input` | \{ `expiresIn?`: `number`; `now?`: `number`; `pieceCid`: [`Uint8Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array); \} |
| `input.expiresIn?` | `number` |
| `input.now?` | `number` |
| `input.pieceCid` | [`Uint8Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array) |

## Returns

[`Promise`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise)\<`string`\>

## Throws

As `signRequest` does: an expired chain, or an expiry the gate would refuse.