no-decrypt oracle user

If you don't want to lock user account in oracle database and nobody knows, gets, cracked password of user, you can use this command
SQL> alter user <username>identified by values 'no-decrypt';

For example:
#sqlplus / as sysdba
SQL>  create user passtest identified by passtest;
User created.
SQL> grant connect to passtest;
Grant succeeded.
#sqlplus passtest/passtest
SQL*Plus: Release 11.2.0.2.0 Production on Wed Nov 23 13:55:10 2011
Copyright (c) 1982, 2010, Oracle.  All rights reserved.


#sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Wed Nov 23 13:58:06 2011
Copyright (c) 1982, 2010, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> alter user passtest identified by values 'no-decrypt';
User altered.


#sqlplus passtest/passtest
SQL*Plus: Release 11.2.0.2.0 Production on Wed Nov 23 13:59:08 2011
Copyright (c) 1982, 2010, Oracle.  All rights reserved.
ERROR:
ORA-01017: geçersiz kullanıcı adı/parolası; oturum açma reddedildi