EMA C++ Developers Guide : 6 Consuming Data from the Cloud : 6.2 Encrypted Connections
 
6.2 Encrypted Connections
When connecting to an LSEG Real-Time Advanced Distribution Server in the cloud, you must use a ChannelType of RSSL_ENCRYPTED (for details on ChannelType, refer to the Enterprise Message API C++ Configuration Guide).
Encrypted connections to the cloud must use an OpenSSL-based connection type (on both Windows and Linux). WinINet is not supported for cloud connectivity.