CoQueryAuthenticationServices function (combaseapi.h)

Retrieves a list of the authentication services registered when the process called CoInitializeSecurity.


HRESULT CoQueryAuthenticationServices(
  [out] DWORD                       *pcAuthSvc,


[out] pcAuthSvc

A pointer to a variable that receives the number of entries returned in the asAuthSvc array.

[out] asAuthSvc

A pointer to an array of SOLE_AUTHENTICATION_SERVICE structures. The list is allocated through a call to the CoTaskMemAlloc function. The caller must free the list when finished with it by calling the CoTaskMemFree function.

Return value

This function can return the standard return values E_INVALIDARG, E_OUTOFMEMORY, and S_OK.


CoQueryAuthenticationServices retrieves a list of the authentication services currently registered. If the process calls CoInitializeSecurity, these are the services registered through that call. If the application does not call it, CoInitializeSecurity is called automatically by COM, registering the default security package, the first time an interface is marshaled or unmarshaled.

This function returns only the authentication services registered with CoInitializeSecurity. It does not return all of the authentication services installed on the computer, but EnumerateSecurityPackages does. CoQueryAuthenticationServices is primarily useful for custom marshalers, to determine which principal names an application can use.

Different authentication services support different levels of security. For example, NTLMSSP does not support delegation or mutual authentication while Kerberos does. The application is responsible only for registering authentication services that provide the features the application needs. This function provides a way to find out which services have been registered with CoInitializeSecurity.


Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header combaseapi.h (include Objbase.h)
Library Ole32.lib
DLL Ole32.dll

See also



Security in COM