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# Basic authentication

> How to configure basic authentication in an adapter, including standard setup and common variations.

Basic authentication is a widely supported standard for authenticating to external systems. It is not always the most secure method, as credentials can be exposed if the connection is not properly secured.

In standard basic authentication:

1. The username and password are concatenated with a colon to form a credential string: `username:password`.
2. The credential string is base64-encoded so credentials are not transmitted in the clear.
3. The resulting string is prefixed with `Basic `.
4. The final string is placed in the `Authorization` header of every request.

## Configure basic authentication

Basic authentication is configured entirely in the `authentication` section of the Itential Platform service instance configuration for the adapter, accessible through Itential Platform Admin Essentials. For a full description of all authentication properties, see [Service instance configuration](/adapters/configure/service-instance-configuration/properties/overview).

Set the following properties:

* Set `auth_method` to `"basic_user_password"`.
* Set `username` and `password` to the credentials for the external system. The `password` field can be encrypted using Itential Platform's encryption.
* Set `auth_field` to the location in the request where the credentials should be placed. Headers are the most common placement, referenced as `header.headers.<field-name>`. For the standard `Authorization` header, use `header.headers.Authorization`.
* Set `auth_field_format` to the format of the credential string. The adapter library substitutes the following variables at runtime:
  * `{username}`
  * `{password}`
  * `{b64}…{/b64}` — base64-encodes everything between the tags

### Example

```json
"authentication": {
  "auth_method": "basic_user_password",
  "username": "systemuser",
  "password": "systempassword",
  "auth_field": "header.headers.Authorization",
  "auth_field_format": "Basic {b64}{username}:{password}{/b64}"
}
```

## Variations

Some systems use variations of basic authentication. The following table describes common options and how to configure them.

| Variation                                    | Configuration                                                                          |
| -------------------------------------------- | -------------------------------------------------------------------------------------- |
| Credentials in a different header field      | Set `auth_field` to `"header.headers.MyAuthField"`.                                    |
| Credentials in the URL path (before the `?`) | Set `auth_field` to `"urlpath"`.                                                       |
| Credentials in the URL query (after the `?`) | Set `auth_field` to `"url"`.                                                           |
| Credentials in the request body              | Set `auth_field` to `"body.field"`.                                                    |
| Different credential format                  | Set `auth_field_format` to the required format, for example `"{username},{password}"`. |

### Example: credentials in a custom header with a different format

```json
"authentication": {
  "auth_method": "basic_user_password",
  "username": "systemuser",
  "password": "systempassword",
  "auth_field": "header.headers.MyAuthField",
  "auth_field_format": "{username},{password}"
}
```

> How to configure basic authentication in an adapter, including standard setup and common variations.