How to encrypt and decrypt a file in Linux ?

There could be few ways to Encrypt and Decrypt a file in Linux. The one which I use is, gpg (GnuPG).
Below shown are the steps to encrypt and decrypt a file called "confidential.txt".

[root@hostxyz ashok]# echo 'newpassXYZ' > confidentail.txt
[root@hostxyz ashok]# cat confidentail.txt
newpassXYZ
[root@hostxyz ashok]# gpg -c confidential.txt
Enter passphrase:  <secret word>
Repeat passphrase: <secret word>
[root@hostxyz ashok]# ls -l confidentail.*
-rw-r--r-- 1 root root 11 May 22 22:01 confidential.txt
-rw-r--r-- 1 root root 66 May 22 22:01 confidential.txt.gpg
[root@hostxyz ashok]# cat confidential.txt.gpg
ê2Ãà pisÃu?î^ó5Ã\<dÃ
â[root@hostxyz ashok]# mv confidential.txt.gpg /tmp
[root@hostxyz ashok]# cd /tmp
[root@hostxyz tmp]# gpg -d confidential.txt.gpg
gpg: CAST5 encrypted data
Enter passphrase:  <secret word>
[root@hostxyz tmp]# cat confidential.txt
newpassXYZ
[root@hostxyz tmp]#

The config file for 'gpg' is /root/.gnupg/gpg.conf