To encrypt single file, use command gpg as follows:
$ gpg -c filename
This will create a myfinancial.info.gpg file.
-c : Encrypt with symmetric cipher.
Caution if you ever forgot your password aka passphrase, you cannot
recover the data as it use very strong encryption.
Task: decrypt file
To decrypt file use gpg command:
$ gpg myfinancial.info.gpg
gpg: CAST5 encrypted data
Decrypt file and write output to file vivek.info.txt you can run command:
$ gpg myfinancial.info.gpg –o vivek.info.txt