# ft_auth · FT4 Rell API · Chromia Docs (concept)

> @mount("ft4.ft_ auth")
operation ft_ auth(account_ id: byte_ array, auth_ descriptor_ id: byte_ array) For an operation to be authorized by an FT signer, t

Source: https://docs.chromia.com/pages/ft4-rell/-f-t4-library/lib.ft4.external.auth/ft_auth/

OPERATION

# ft\_auth

```signature
@mount("ft4.ft_auth")
operation ft_auth(account_id: byte_array, auth_descriptor_id: byte_array)
```

[Source](https://gitlab.com/chromaway/ft4-lib/-/blob/development/rell/src/lib/ft4/external/auth/operations.rell#lines-101)

For an operation to be authorized by an FT signer, this operation must be called beforehand.

The transaction must then contain

* ft\_auth
* the operation that is being authorized

with nothing else inbetween them. Other operations may be added before and after these two.
The whole transaction must be signed by all the signers that are required by the auth
descriptor.

Throws if the next operation is blacklisted or this is the last operation in the transaction

**Parameters**

* **account\_id** — The ID of the account that is calling the next operation
* **auth\_descriptor\_id** — The ID of the auth descriptor that is authorizing the operation

**See Also**

* `core.auth._auth_handler` — for more details on operation authorization

[View this page on docs.chromia.com](https://docs.chromia.com/pages/ft4-rell/-f-t4%20-library/lib.ft4.external.auth/ft_auth.html)Generated API reference, mirrored from the live docs