title: Using Microsoft Graph token to secure ASP.NET Core Web API with Jwt Bearer tokens
body: <p>We have an ASP.NET Core Web API that I want to secure with Microsoft Graph Access token. The graph token is valid and I can do graph call it works fine.</p>
  
  <p>However, If I try to access the ASP.NET Core Web API which is configured with JWT Bearer authentication, it gives the following error.</p>
  
  <blockquote>
    <p>Bearer error="invalid_token", error_description="The signature key
    was not found</p>
  </blockquote>
  
  <p>Am I missing some configurations to configure or this is a problem with graph token? Here is how the authentication is configured.</p>
  
  <pre><code>        services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                 .AddJwtBearer(options =&gt;
                 {
                     options.TokenValidationParameters = new TokenValidationParameters()
                     {
                         ValidateIssuer = false, // For multi tenant
                         ValidateIssuerSigningKey = false,
                         ValidateAudience = false // This is for testing
                     };
                 });
  </code></pre>
  
  <p>The same configurations works fine with Azure AD Access Token.</p>