Why Hash?

• Verify integrity

people use md5 to gurantee the integrity of iso files, while sha1 is safer.

• speed up database search

The RSA algorithm was publicly described in 1978 by Ron Rivest, Adi Shamir, and Leonard Adleman at MIT; the letters RSA are the initials of their surnames.

tools

• seahorse
• gpg
• pgp

what I need

• private

lock a folder to non-root

root@girl:/home/pet/Desktop# chown root dd
root@girl:/home/pet/Desktop# chgrp root dd
root@girl:/home/pet/Desktop# chmod -r dd
root@girl:/home/pet/Desktop# ls -l dd
total 0
-rw-r--r-- 1 pet pet 0 2009-11-23 11:22 dd
---
pet@girl:~/Desktop/dd$ ls
ls: cannot open directory .: Permission denied
pet@girl:~/Desktop/dd$

or maybe this way as a much easier solution

Just chmod them to 000, it will then require root access to view them.