Pre-authenticated requests provide a way to let you access a bucket or an object without having your own credentials. For example, you can create a request that lets you upload backups to a bucket without owning API keys.
When you create a bucket, the bucket is considered a private bucket and the access to the bucket and bucket contents requires authentication and authorization. However, Object Storage supports anonymous, unauthenticated access to a bucket. You make a bucket public by enabling read access to the bucket.
pre-authenticated requests have to select expiration date