Importing CA-Signed Certificates from the Database Server
Note: The CA-signed certificates for your database server must be
                provided to you by your system administrator.
        Use the following commands to load CA-signed certificates for your Oracle database client wallet:
Root Certificate
orapki wallet add -wallet <wallet_path> -pwd WalletPasswd123 -trusted_cert
                -cert rootca.pem 
Example:
orapki wallet add -wallet "/u01/app/oracle/wallet" -pwd WalletPasswd123
                -trusted_cert -cert c:\rootca.pem
Intermediate Certificate
orapki wallet add -wallet <wallet_path> -pwd WalletPasswd123 -trusted_cert
                -cert interca.pem
Example:
orapki wallet add -wallet "/u01/app/oracle/wallet" -pwd WalletPasswd123
                -trusted_cert -cert c:\interca.pem