[oracle@station200 mywallet]$ pwd
/u01/app/oracle/product/11.2.0/dbhome_1/mywallet
[oracle@station200 mywallet]$ ls
ewallet.p12
[oracle@station200 mywallet]$ du -sh ewallet.p12
4.0K ewallet.p12
SQL> alter system set encryption key identified by "oracle12";
alter system set encryption key identified by "oracle12"
*
ERROR at line 1:
ORA-28353: failed to open wallet