With puttygen tool you can create your private, public, and open ssh keys for Cloud instances, here the procedure:
1.- Open tool
2.- Select SSH-2 RSA
3- Bits:
4- Generate:
5- Draw stg for randomness
6.- Copy key
7.- Set the key pass phrase to create a private key
There is no way to recover a passphrase if you forget it.
8.- Save it (PPK Extension)
9.- If you need to create a compatible SSH key for commands, export it as open ssh.
10.- Create public key by copy-paste the content of the generated key,point 6, in a txt file and save it.
Note: Not the private key
More information:
http://www.oracle.com/webfolder/technetwork/tutorials/obe/cloud/dbaas/obe_dbaas_QS/oracle_database_cloud_service_dbaas_quick_start.html#section1
