BlobStorage.Advanced.GetBlobSasUri C# (CSharp) Method

        private static string GetBlobSasUri(CloudBlobContainer container, string blobName, string policyName = null)
        {
            string sasBlobToken;

            // Get a reference to a blob within the container.
            // Note that the blob may not exist yet, but a SAS can still be created for it.
            CloudBlockBlob blob = container.GetBlockBlobReference(blobName);

            if (policyName == null)
            {
                // Create a new access policy and define its constraints.
                // Note that the SharedAccessBlobPolicy class is used both to define the parameters of an ad-hoc SAS, and 
                // to construct a shared access policy that is saved to the container's shared access policies. 
                SharedAccessBlobPolicy adHocSAS = new SharedAccessBlobPolicy()
                {
                    // When the start time for the SAS is omitted, the start time is assumed to be the time when the storage service receives the request. 
                    // Omitting the start time for a SAS that is effective immediately helps to avoid clock skew.
                    SharedAccessExpiryTime = DateTime.UtcNow.AddHours(24),
                    Permissions = SharedAccessBlobPermissions.Read | SharedAccessBlobPermissions.Write | SharedAccessBlobPermissions.Create
                };

                // Generate the shared access signature on the blob, setting the constraints directly on the signature.
                sasBlobToken = blob.GetSharedAccessSignature(adHocSAS);

                Console.WriteLine("SAS for blob (ad hoc): {0}", sasBlobToken);
                Console.WriteLine();
            }
            else
            {
                // Generate the shared access signature on the blob. In this case, all of the constraints for the
                // shared access signature are specified on the container's stored access policy.
                sasBlobToken = blob.GetSharedAccessSignature(null, policyName);

                Console.WriteLine("SAS for blob (stored access policy): {0}", sasBlobToken);
                Console.WriteLine();
            }

            // Return the URI string for the container, including the SAS token.
            return blob.Uri + sasBlobToken;
        }