> For the complete documentation index, see [llms.txt](https://developers-apps-in-toss.toss.im/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers-apps-in-toss.toss.im/documentation/sdk/domains-api/tossauth/tossauth.sign.md).

# TossAuth.sign

> 함수형 API `appsInTossSignTossCert`으로도 같은 기능을 쓸 수 있어요.

### 기능 설명

토스 인증서를 사용해 서명해요. `txId`는 토스 인증서를 사용한 본인확인, 간편인증, 전자서명에서 사용하는 Transaction Id예요.

토스앱 Android/iOS `5.233.0` 이상에서 사용할 수 있어요. 미지원 버전에서 호출하면 `UNSUPPORTED_APP_VERSION` 에러가 발생해요.

### 타입

```ts
TossAuth.sign(params: AppsInTossSignTossCertParams): Promise<void>;
```

**Params**

```ts
type AppsInTossSignTossCertParams = {
  txId: string;
};
```

**Response**

없음

### 에러 코드

에러 코드는 catch한 에러의 `error.code` 값이에요.

| 코드                        | 설명                                                                                                                              |
| ------------------------- | ------------------------------------------------------------------------------------------------------------------------------- |
| `UNSUPPORTED_APP_VERSION` | 실행 중인 토스앱 버전이 이 기능을 지원하지 않으면 호출 즉시 발생해요. `TossAuth.sign.isSupported()`로 사전 확인하고, 발생 시 `error.message`(업데이트 안내 문구)를 사용자에게 보여주세요. |

### 예시 코드

```js
import { TossAuth } from "@apps-in-toss/web-framework";

const button = document.querySelector("#sign-button");

button.addEventListener("click", async () => {
  try {
    await TossAuth.sign({ txId: "f2e1a6df..." });
  } catch (error) {
    console.error(error);
  }
});
```


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