private static extern int AcceptSecurityContext__(SecHandle phCredential,
     SecHandle phContext, ref SecBufferDescNative pInput, int fContextReq, int TargetDataRep,
     SecHandle phNewContext, ref SecBufferDescNative pOutput, ref int pfContextAttr,
     ref Int64 ptsExpiry);
 private static extern int VerifySignature__(SecHandle phContext,
     ref SecBufferDescNative pMessage, int MessageSeqNo,
     ref int pfQOP);
 private static extern int MakeSignature__(SecHandle phContext, int fQOP, 
     ref SecBufferDescNative pMessage, int MessageSeqNo);
 private static extern int InitializeSecurityContext__(SecHandle phCredential,
     SecHandle phContext, string pszTargetName, int fContextReq, int Reserved1,
     int TargetDataRep, ref SecBufferDescNative pInput, int Reserved2, SecHandle phNewContext,
     ref SecBufferDescNative pOutput, ref int pfContextAttr, ref Int64 ptsExpiry);
 private static extern int EncryptMessage__(SecHandle phContext,
     int pfQOP, ref SecBufferDescNative pMessage, int MessageSeqNo);
 private static extern int DecryptMessage_NT(SecHandle phContext,
     ref SecBufferDescNative pMessage, int MessageSeqNo,
     ref int pfQOP);