The following two constants are used by to specify the level of security to use to open objects from a directory service. They are used in IADsOpenDSObject and documented by each system provider. See ADSI System Providers.
#define ADS_SECURE_AUTHENTICATION ( 0x1 )
#define ADS_USE_ENCRYPTION ( 0x2 )
#define ADS_READONLY_SERVER ( 0x4 )