Hi ,
You can use the crypt command in unix to do this.

ex.

Create a file which has the clear passwd (/tmp/testpw)
encrypt

crypt Key<clear_passwd.file > encrypt_file

crypt 123 < /tmp/testpw > /tmp/testcr

Now you can remove the clear passwd file .. But you should remeber the key.

You can connect to the oracle in the following way.

sqlplus "user_name/`crypt 123 < /tmp/testcr`"

SQL*Plus: Release 9.2.0.5.0 - Production on Fri Mar 4 08:32:25 2005

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.


Connected to:
Oracle9i Enterprise Edition Release 9.2.0.5.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.5.0 - Production

SQL>


Please check is this helps you.

Thanks and Regards

Bala