Encrypt packet

[Vladimir Sabanov]

Hi! I have some transport which based on winsock. Client(FTPS) send to
me some data over SSL, and i receive it with (for example):

...
if (WSARecv(AcceptSocket, &DataBuf, 1, &RecvBytes, &Flags, 
&AcceptOverlapped, NULL) == SOCKET_ERROR){
     if (WSAGetLastError() != WSA_IO_PENDING)
          printf("Error occured at WSARecv()\n");
}
...

DataBuf is complete packet.Question:
how can i decrypt received data in DataBuf, if i have certificate, puclic 
and private keys?

NOTE: i cannot use SSL_read and SSL_write in this task...:(

Thanks for support!