What is Shared Access Signature

A shared access signature (SAS) is a URI that grants restricted access rights to Azure Storage resources. You can provide a shared access signature to clients who should not be trusted with your storage account key but to whom you wish to delegate access to certain storage account resources. By distributing a shared access signature URI to these clients, you can grant them access to a resource for a specified period of time, with a specified set of permissions.

The URI query parameters comprising the SAS token incorporate all of the information necessary to grant controlled access to a storage resource. A client who is in possession of the SAS can make a request against Azure Storage with just the SAS URI, and the information contained in the SAS token is used to authorize the request.