A shared access signature token (SAS token)
From: https://learn.microsoft.com/en-us/azure/storage/common/storage-sas-overview
A shared access signature (SAS) provides secure delegated access to resources in your storage account without compromising the security of your data. With a SAS token, you have granular control over how a client can access your data. You can control what resources the client may access, what permissions they have on those resources, and how long the SAS is valid, among other parameters.
How a shared access signature works A shared access signature is a signed URI that points to one or more storage resources and includes a token that contains a special set of query parameters. The token indicates how the resources may be accessed by the client. One of the query parameters, the signature, is constructed from the SAS parameters and signed with the key that was used to create the SAS. This signature is used by Azure Storage to authorize access to the storage resource.