public class SecurityHeadersPolicy 
{
 public IDictionary<string, string> SetHeaders { get; }
  = new Dictionary<string, string>();
 
 public ISet<string> RemoveHeaders { get; }
 = new HashSet<string>();
}

public class SecurityHeadersMiddleware 
{
 private readonly RequestDelegate _next;
 private readonly SecurityHeadersPolicy _policy;

 public SecurityHeadersMiddleware(RequestDelegate next, SecurityHeadersPolicy policy)
 {
 _next = next;
 _policy = policy;
 }

 public async Task Invoke(HttpContext context)
 { 
 IHeaderDictionary headers = context.Response.Headers;

 foreach (var headerValuePair in _policy.SetHeaders)
 {
  headers[headerValuePair.Key] = headerValuePair.Value;
 }

 foreach (var header in _policy.RemoveHeaders)
 {
  headers.Remove(header);
 }

 await _next(context);
 }
}

public static class MiddlewareExtensions 
{
 public static IApplicationBuilder UseSecurityHeadersMiddleware(this IApplicationBuilder app, SecurityHeadersBuilder builder)
 {
 SecurityHeaderPolicy policy = builder.Build();
 return app.UseMiddleware<SecurityHeadersMiddleware>(policy);
 }
}

public class SecurityHeadersBuilder 
{
 private readonly SecurityHeadersPolicy _policy = new SecurityHeadersPolicy();

 public SecurityHeadersBuilder AddDefaultSecurePolicy()
 {
 AddFrameOptionsDeny();
 AddXssProtectionBlock();
 AddContentTypeOptionsNoSniff();
 AddStrictTransportSecurityMaxAge();
 RemoveServerHeader();

 return this;
 }

 public SecurityHeadersBuilder AddFrameOptionsDeny()
 {
 _policy.SetHeaders[FrameOptionsConstants.Header] = FrameOptionsConstants.Deny;
 return this;
 }

 public SecurityHeadersBuilder AddFrameOptionsSameOrigin()
 {
 _policy.SetHeaders[FrameOptionsConstants.Header] = FrameOptionsConstants.SameOrigin;
 return this;
 }

 public SecurityHeadersBuilder AddFrameOptionsSameOrigin(string uri)
 {
 _policy.SetHeaders[FrameOptionsConstants.Header] = string.Format(FrameOptionsConstants.AllowFromUri, uri);
 return this;
 }

 public SecurityHeadersBuilder RemoveServerHeader()
 {
 _policy.RemoveHeaders.Add(ServerConstants.Header);
 return this;
 }

 public SecurityHeadersBuilder AddCustomHeader(string header, string value)
 {
 _policy.SetHeaders[header] = value;
 return this;
 }

 public SecurityHeadersBuilder RemoveHeader(string header)
 {
 _policy.RemoveHeaders.Add(header);
 return this;
 }

 public SecurityHeadersPolicy Build()
 {
 return _policy;
 }
}

app.UseSecurityHeadersMiddleware(new SecurityHeadersBuilder() 
.AddDefaultSecurePolicy()
);

HTTP/1.1 200 OK 
Content-Type: text/html; charset=utf-8 
X-Frame-Options: DENY 
X-XSS-Protection: 1; mode=block 
X-Content-Type-Options: nosniff 
Strict-Transport-Security: max-age=31536000 
X-Powered-By: ASP.NET

@Html.AntiForgeryToken()

[ValidateAntiForgeryToken]
[HttpPost]
public IActionResult AntiForm(string message)
{
return Content(message);
}