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

> @extendable function before_ authenticate(account: account , account_ auth_ descriptor: account_ auth_ descriptor ) This function can be extended by users 

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

FUNCTION

# before\_authenticate

```signature
@extendable function before_authenticate(account: account, account_auth_descriptor: account_auth_descriptor)
```

[Source](https://gitlab.com/chromaway/ft4-lib/-/blob/development/rell/src/lib/ft4/core/auth/authentication.rell#lines-11)

This function can be extended by users to add custom logic before the authentication of
an operation.

Throws when any extension of this function throws.

**Parameters**

* **account** — the account that is calling the operation
* **account\_auth\_descriptor** — the auth descriptor that is authenticating as account

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