Controlling Default Tablespace Encryption
The ENCRYPT_NEW_TABLESPACES initialization parameter controls default encryption of new tablespaces. In Database Classic Cloud Service databases, this parameter is set to CLOUD_ONLY by default. See Viewing and Modifying Initialization Parameters for additional information.
https://docs.oracle.com/en/cloud/paas/database-dbaas-cloud/csdbi/use-tablespace-encryption-this-service.html#GUID-26B5DB17-E631-4C2D-A172-C02C0D8C1D14

https://docs.cloud.oracle.com/en-us/iaas/Content/Database/Tasks/migrating.htm Migration Connectivity Options You have several connectivity options when migrating your on-premises databases to the Oracle Cloud Infrastructure. The options are listed below in order of preference.
FastConnect: Provides a secure connection between your existing network and your virtual cloud network (VCN) over a private physical network instead of the internet. For more information, see FastConnect.
IPSec VPN: Provides a secure connection between a dynamic routing gateway (DRG) and customer-premise equipment (CPE), consisting of multiple IPSec tunnels. The IPSec connection is one of the components forming a site-to-site VPN between a VCN and your on-premises network. For more information, see VPN Connect.
Internet gateway: Provides a path for network traffic between your VCN and the internet. For more information, see Internet Gateway.