There are a number of options available for access management of your buckets and objects. Let's see a summary:

1. Identity and Access Management (IAM) permissions: Gives broad level control for your projects and buckets. It is useful to grant access to buckets and allow bulk operations on objects within a bucket.
2. Access Control Lists (ACLs): Gives you fine-grained control to grant read or write access to users to individual buckets or objects.
3. Signed URLs (query string authentication): Grant read or write access to an object for a limited time period through a Signed URL.
4. Signed Policy Documents: Allows you to define rules and perform validations for what objects can be uploaded in a bucket, for example, restrict based on file size or content-type.
5. Firebase Security Rules: Provides granular and attribute-based rule language to provide access to mobile apps and web apps using the Firebase SDKs for Cloud Storage.

Now that we are familiar with the key concepts of Google Cloud Storage, let's come back to Cloud Storage for Firebase.