> For the complete documentation index, see [llms.txt](https://rest-api.symphony.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://rest-api.symphony.com/main/apps-on-behalf-of-obo/obo-rsa-user-authentication-by-user-id.md).

# User Authentication by User ID

{% openapi src="/files/QTYCdVMbKdCr4AG0pr4r" path="/pubkey/app/user/{userId}/authenticate" method="post" expanded="true" fullWidth="true" %}
[login-api-public.yaml](https://544392450-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F909t04Fk8FiEI7fBcmlw%2Fuploads%2Fgit-blob-0a6a293d0a6cdb3b172f2d2f3cb550af3be41315%2Flogin-api-public.yaml?alt=media)
{% endopenapi %}

> #### 📘 Requirements
>
> The app must have been created on the pod.\
> The app must be enabled.\
> The user must exist and have the app installed. For more information, refer to [Update user Apps](/main/apps-entitlements/partial-update-user-apps.md).