Authorizing access to Azure Storage

Each time you access data in your storage account, your client makes a request over HTTP/HTTPS to Azure Storage. Every request to a secure resource must be authorized, so that the service ensures that the client has the permissions required to access the data.

The following table describes the options that Azure Storage offers for authorizing access to resources:

Shared Key (storage account key) Shared access signature (SAS) Azure Active Directory (Azure AD) Anonymous public read access
Azure Blobs Supported Supported Supported Supported
Azure Files (SMB) Supported Not supported Supported, only with AAD Domain Services Not supported
Azure Files (REST) Supported Supported Not supported Not supported
Azure Queues Supported Supported Supported Not supported
Azure Tables Supported Supported Not supported Not supported

Each authorization option is briefly described below:

  • Azure Active Directory (Azure AD) integration for blobs, and queues. Azure AD provides role-based access control (RBAC) for fine-grained control over a client's access to resources in a storage account. For more information regarding Azure AD integration for blobs and queues, see Authenticating requests to Azure Storage using Azure Active Directory.

  • Azure AD Domain Services (DS) integration (preview) for files. Azure Files supports identity-based authentication over Server Message Block (SMB) through Azure AD DS. This provides RBAC for fine-grained control over a client's access to resources in a storage account. For more information regarding Azure AD integration for files using domain services, see Overview of Azure Files Azure Active Directory Domain Service (AAD DS) Authentication Support for SMB Access (preview).

  • Shared Key authorization for blobs, files, queues, and tables. A client using Shared Key passes a header with every request that is signed using the storage account access key. For more information, see Authorize with Shared Key.

  • Shared access signatures for blobs, files, queues, and tables. Shared access signatures (SAS) provide limited delegated access to resources in a storage account. Adding constraints on the time interval for which the signature is valid or on permissions it grants provides flexibility in managing access. For more information, see Using shared access signatures (SAS).

  • Anonymous public read access for containers and blobs. Authorization is not required. For more information, see Manage anonymous read access to containers and blobs.

By default, all resources in Azure Storage are secured, and are available only to the account owner. Although you can use any of the authorization strategies outlined above to grant clients access to resources in your storage account, Microsoft recommends using Azure AD when possible for maximum security and ease of use.