[Flag] MUTUAL_AUTH [Description] 
The communicating parties must authenticate their identities to each other. Without MUTUAL_AUTH, the client authenticates its identity to the server. With MUTUAL_AUTH, the server also must authenticate its identity to the client. When using the Schannel security package, the server sets the ASC_RET_MUTUAL_AUTH constant only in the last call to AcceptSecurityContext (Negotiate), after certificate mapping has successfully completed.