Creating:

Hub UI will allow users to select a specific set of collection versions to 

perform on-demand signing.

Hub will be able to sign content automatically during the approval process.

Depends on: Pulp-Ansible to expose an API/Task to sign a content using the specified Signing Service.

Exposing:

Hub UI 

    visual indication to identify the signed content.

    filtering collections based on signatures.

    download the signatures along with collections.

Depends on: Pulp Signing API & Hub API endpoints

Hub API will expose signature metadata 

along with collections.

When syncing collections from a remote Hub, signatures will also be synced.

*Hub will not perform any signature verification, this task is deferred to the ansible-galaxy CLI.

Depends on: 

Pulp Ansible to provide the Signature storage and its APIs.
Pulp Ansible to sync signatures along with collections.