Secure Azure Storage API


AAD App Registration

  • Decide if you want to allow users to sign in only if they belong to your organization.
  • Request scope permissions. For example, “” scope.
  • Define scopes that define access to your web API. These are the scopes that you define.
  • Share a secret with the Microsoft identity platform that proves the app’s identity.

Generate Code

dotnet new webapi -au SingleOrg -o SecureApi
cd SecureApi
dotnet add package Azure.Identity
dotnet add package Azure.Storage.Blobs
The type of authentication to use
None - No authentication
IndividualB2C - Individual authentication with Azure AD B2C
SingleOrg - Organizational authentication for a single tenant
Windows - Windows authentication
Default: None

Develop Code From Local

The plan is to get parameter values from appsettings, including storage account name and tenant id . You may not want to check in all these settings to code repo.

  • Update .vscode/launch.json, “ASPNETCORE_ENVIRONMENT”: “Local”
  • Add appsettings.Local.json file, and update it with actual values for local development only
  • Leave appsettings.json with place holder values
  • Add appsettings.Local.json file to .gitignore
  • git reset appsettings.Local.json
    (so that won’t commit the file and won’t push it to repo)
"AzureAd": {
"Instance": "",
"Domain": "need to update",
"TenantId": "need to update ",
"ClientId": "need to update ",
"Scopes": "ToDoList.Read ToDoList.Write",
"CallbackPath": "/signin-oidc"
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft.AspNetCore": "Warning"
"AllowedHosts": "*",
"AzureStorage": {
"AcctName": "need to update tbd",
"ContainerName": "need to update tbd"

Customize Code

Add MyBlobFile.cs and remove WeatherForecast.cs:

namespace SecureApi;
public class MyBlobFile
public string? BlobFile { get; set; }
public DateTimeOffset? LastModified { get; set; }


C:\WINDOWS\system32>az login --scope api://<api service app registration client id>/ToDoList.Read api://<api service app registration client id>/ToDoList.Write
C:\WINDOWS\system32>az account get-access-token --scope "api://<api service app registration client id>/ToDoList.Read api://<api service app registration client id>/ToDoList.Write"
"accessToken": "eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIs....",
"expiresOn": "2022-06-10 23:53:19.000000",
"subscription": "24c9c37c-bf59-4b84-907c-43819602e881",
"tenant": "9b2ec8d7-37b8-4aac-acd2-9ed0acfb1c5a",
"tokenType": "Bearer"
"aud": "api service app registration client id",
"iss": "<tenant id>/v2.0",
"scp": "ToDoList.Read ToDoList.Write",
"ver": "2.0"
$ curl -k -X 'POST'  'https://localhost:7249/MyBlobFile'   -H 'accept: text/plain'  -H 'Content-Type: application/json' -H 'Authorization: bearer eyJ0eXAiOiJKV1Q....'  -d '{  "blobFile": "dummy.txt"}'
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 45 100 18 100 27 1 1 0:00:27 0:00:14 0:00:13 4
dummy file line #1


It requires almost no coding to secure an API using MS identity platform, in next blog, we will add angular UI code to sing in user and call the secured API.




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Cloud Journey

Cloud Journey

All blogs are strictly personal and do not reflect the views of my employer, focus on cloud networking, cloud security and API security.