Regarding Configure AAD Integration using ASPNet Core 2.1 Web API - azure

Question

I already have a AAD integrated WebAPP using ASP.Net Core 2.1 but now i want to develop an API using ASPNet Core 2.1 to authenticate AAD user to my api using JWT bearer token. I am unable to perform the same because in web app i am using Cookie Auth mode but here i need to implement JWT Bearer which was not working for me. I tried a lot of code from different code repo.
References:
https://github.com/juunas11/Joonasw.AzureAdApiSample
https://github.com/Azure-Samples/active-directory-b2c-dotnetcore-webapi
https://azure.microsoft.com/en-in/resources/samples/active-directory-dotnet-native-aspnetcore-v2/
services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
.AddJwtBearer(options =>
{
options.Audience = "https://localhost:44395/";
options.Authority = "https://localhost:44395/identity/";
})
.AddJwtBearer("AzureAD", options =>
{
options.Audience = "https://localhost:44395/";
options.Authority = "https://login.microsoftonline.com/tenantID/";
});
services.AddAuthorization(options =>
{
var defaultAuthorizationPolicyBuilder = new AuthorizationPolicyBuilder(
JwtBearerDefaults.AuthenticationScheme,
"AzureAD");
defaultAuthorizationPolicyBuilder =
defaultAuthorizationPolicyBuilder.RequireAuthenticatedUser();
options.DefaultPolicy = defaultAuthorizationPolicyBuilder.Build();
});
When i am changing the mode to Cookie Mode it is working fine but not working in JWTBearer code.
Microsoft.AspNetCore.Authorization.DefaultAuthorizationService:Information: Authorization failed.
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker:Information: Authorization failed for the request at filter 'Microsoft.AspNetCore.Mvc.Authorization.AuthorizeFilter'.
Microsoft.AspNetCore.Mvc.ChallengeResult:Information: Executing ChallengeResult with authentication schemes (Bearer, AzureAD).
Microsoft.AspNetCore.Authentication.JwtBearer.JwtBearerHandler:Information: AuthenticationScheme: Bearer was challenged.
Microsoft.AspNetCore.Authentication.JwtBearer.JwtBearerHandler:Information: AuthenticationScheme: AzureAD was challenged.
Could anyone help me here? I am stuck here due to this issue.
Thanks in advance

Answer 1

Suppose you have REST API resources written in ASP.NET Core Web API which protected by Azure AD , the client(ASP.NET Web application) can use the OpenID Connect middleware and the Active Directory Authentication Library (ADAL.NET) to obtain a JWT bearer token for the signed-in user using the OAuth 2.0 protocol.
The bearer token is passed to the web API, which validates the token and authorizes the user using the JWT bearer authentication middleware, for example , refer to code sample in first link :
services
.AddAuthentication(o =>
{
o.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
})
.AddJwtBearer(o =>
{
o.Authority = Configuration["Authentication:Authority"];
o.TokenValidationParameters = new Microsoft.IdentityModel.Tokens.TokenValidationParameters
{
// Both App ID URI and client id are valid audiences in the access token
ValidAudiences = new List<string>
{
Configuration["Authentication:AppIdUri"],
Configuration["Authentication:ClientId"]
}
};
});
Above code sample use JwtBearerExtensions to validate the access token . You could click here for explanation about scenario.