CloudBlob.GetSharedAccessSignature Method (SharedAccessPolicy, String)

static void WriteToBlobViaSAS2(Uri blobEndpoint, string accountName, string accountKey)
{
    // Create a service client for credentialed access to the Blob.
    CloudBlobClient blobClient = new CloudBlobClient(blobEndpoint, new StorageCredentialsAccountAndKey(accountName, accountKey));

    // Create a CloudBlobContainer reference object.
    CloudBlobContainer container = blobClient.GetContainerReference("mySASContainer");

    // Create a new blob container in the cloud if the CloudBlobContainer reference
    // doesn't reference an existing container.
    container.CreateIfNotExist();

    // Create a BlobContainerPermissions dictionary object.
    // This holds a collection of individual SharedAccessPolicy objects.
    BlobContainerPermissions containerPermissions = new BlobContainerPermissions();

    // Create a SharedAccessPolicy object.
    SharedAccessPolicy myCAPolicy = new SharedAccessPolicy();

    // Initialize the SharedAccessPolicy object.
    // Configure the policy to go into effect an hour from now, 
    // to remain in effect for a ten-hour duration,
    // and grant read/write permissions to the data.
    myCAPolicy.SharedAccessStartTime  = DateTime.UtcNow.AddHours(1);
    myCAPolicy.SharedAccessExpiryTime = DateTime.UtcNow.AddHours(11);
    myCAPolicy.Permissions = SharedAccessPermissions.Write | SharedAccessPermissions.Read;

    // Add this SharedAccessPolicy object to the BlobContainerPermissions dictionary.
    containerPermissions.SharedAccessPolicies.Add("myContainerPolicy", myCAPolicy);

    // Restrict anonymous access to the container contents.
    containerPermissions.PublicAccess = BlobContainerPublicAccessType.Off;

    // Apply the collection of shared access policies (in this case, only one policy)
    // to the container.
    container.SetPermissions(containerPermissions);

    // Create a blob reference object.
    CloudBlob blob = blobClient.GetBlobReference("mySASContainer/myBlob.txt");

    // Upload text to the blob.
    // This creates a new blob if the CloudBlob reference doesn’t reference an existing blob.
    blob.UploadText("a text blob");

    // Create a shared access signature to use for delegated access to the blob.
    // Note that this call passes in an empty access policy so that the shared access signature 
    // will use the 'myContainerPolicy' shared access policy defined for the container.
    string signature = blob.GetSharedAccessSignature(new SharedAccessPolicy(), "myContainerPolicy");

    // Use the shared access signature to get another reference to the blob.
    CloudBlob blobSAS = new CloudBlob("http://storagesample.blob.core.windows.net/mySASContainer/myBlob.txt",
                                      new StorageCredentialsSharedAccessSignature(signature));

    // Update the contents of the blob.
    blobSAS.UploadText("A text blob updated using a shared access signature");

    // Output the contents of the blob.
    Console.WriteLine(blobSAS.DownloadText());
}