Process for downloading Blob file using SAS token
Azure Blob storage
Azure Blob storage is Microsoft’s object storage solution for the cloud. Blob storage is optimized for storing massive amounts of unstructured data. Unstructured data is data that doesn’t adhere to a particular data model or definition, such as text or binary data.
Blob storage resources
Blob storage offers three types of resources:
- The storage account
- A container in the storage account
- A blob in a container
The following diagram shows the relationship between these resources.

Shared access signatures (SAS) token
The SAS token is a string that you generate on the client-side, for example by using one of the Azure Storage client libraries. The SAS token is not tracked by Azure Storage in any way. You can create an unlimited number of SAS tokens on the client-side. After you create a SAS, you can distribute it to client applications that require access to resources in your storage account.
Flowchart :

Sample C# Code for generating SAS token:
private static string GenearteSas(string container,string blob, string accountName, string accountKey)
{
var account = new CloudStorageAccount(new StorageCredentials(accountName, accountKey), true);
var cloudBlobClient = account.CreateCloudBlobClient();
var containerr = cloudBlobClient.GetContainerReference(container);
var blobb = containerr.GetBlockBlobReference(blob);
Azure.Storage.Sas.BlobSasBuilder blobSasBuilder = new Azure.Storage.Sas.BlobSasBuilder()
{
BlobContainerName =container,
BlobName =blob,
ExpiresOn = DateTime.UtcNow.AddMinutes(5),//Let SAS token expire after 5 minutes.
};
blobSasBuilder.SetPermissions(Azure.Storage.Sas.BlobSasPermissions.Read);//User will only be able to read the blob and it's properties
var sasToken = blobSasBuilder.ToSasQueryParameters(new StorageSharedKeyCredential(accountName, accountKey)).ToString();
}
Example: https://myaccount.blob.core.windows.net/pictures/profile.jpg?{{SAStoken}}

Sample Code reference for other languages:
https://docs.microsoft.com/en-us/rest/api/eventhub/generate-sas-token
I really like your writing!