To encrypt and decrypt files with a password, use gpg command. It is an encryption and signing tool for Linux/UNIX like operating system such as FreeBSD/Solaris.
GnuPG stands for GNU Privacy Guard and is GNU's tool for secure communication and data storage. It can be used to encrypt data and to create digital signatures. It includes an advanced key management facility.
Encrypting a file in linux
To encrypt single file, use command gpg as follows:
$ gpg -c filename
To encrypt myfinancial.info file, type the command:
$ gpg -c myfinancial.info
Output:
Enter passphrase:<YOUR-PASSWORD> Repeat passphrase:<YOUR-PASSWORD>
This will create a myfinancial.info.gpg file.
Option:
- -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
Output:
gpg myfinancial.info.gpg gpg: CAST5 encrypted data Enter passphrase:<YOUR-PASSWORD>
Decrypt file and write output to file vivek.info.txt you can run command:
$ gpg myfinancial.info.gpg –o vivek.info.txt
Remember if file extension is .asc, it is a ASCII encrypted file and if file extension is .gpg, it is a binary encrypted file.
See also:
- GnuPG Frequently Asked Questions
- Consult man page of gpg
Featured Articles:
- 20 Linux System Monitoring Tools Every SysAdmin Should Know
- 20 Linux Server Hardening Security Tips
- 10 Greatest Open Source Software Of 2009
- My 10 UNIX Command Line Mistakes
- Top 5 Email Client For Linux, Mac OS X, and Windows Users
- Top 20 OpenSSH Server Best Security Practices
- Top 10 Open Source Web-Based Project Management Software
- Top 5 Linux Video Editor Software
- Email this to a friend
- Download PDF version
- Printable version
- Comment RSS feed
- Last Updated: Aug/10/2007
{ 14 comments… read them below or add one }
Thanks! This helped me a lot. Encryption everywhere seems to be only about e-mail. I just wanted to encrypt a password file.
This came very handy…and is now bookmarked! Thanks.
This is fine as far as it goes. However, if you decrypt a file and look at it using a word processor (say), the word processor might well leave back-up copies of your sensitive file in /tmp or in a back-up directory. So when you delete your unencrypted file, you have to delete any other copies that might be lying around the filing system too. A better way around this problem might be to use whole partition encryption: http://encryptionhowto.sourceforge.net/Encryption-HOWTO-4.html
But even then, you need to watch out for stuff that may be on a different disk/partition, e.g. in /tmp.
David,
Good point about backup files. Thanks for sharing howto links.
Appreciate your post!
Great post.
I need to encript a backup file in non interactive mode, so I do not have a prompt to type the password, because is a automated script.
Do you have how I can proceed?
Tkx in advance.
Sirs,
can i encrypt squid.conf or httpd.conf that are located on /etc/xxx folder… knowing that squid process and apache process need to access this file in order to read the file configuration! if this is not workable in my case… is there a way to hide the .conf files from even the root users.. please your help is highly appreciated…
greetings from lebanon
Regards,
i want to encrypt/hide .conf. your help is highly appreciated…
thank for help I want to decrypt rar files
1) Unless the app is aware of the encryption , you cannot encrypt such .conf files.
2) It is possibles to write a script that wraps the process , i.e squid and call the gpg , decrypt the file and then call the squid , reencrypt the file , delete the .conf …
It is actually bound to how the process calls his conf files ,i.e at the beginning , in the loop …
3) You can even recompile squid with some crypting lib. and change all calls to read file to be proceeded by a decryption function.
4) No body but the root should have the root pass , other users must be in specific groups that enable them to do some stuff that normally only the root can do and hence avoid giving them the root pass.
I thought, even if you encrypt a backup script, it will still run as it is.
But it’s not.
I just want to hide the backup script form others because it contains critical information about the files being backed up.
Jay: I think you will need to create a new backup script that decrypts and reads an encrypted file containing the critical information about the files being backed up.
The information about the files will be protected, and the script should still run normally.
It’s very nice stuff … encryption and decryption in linux and tell me how to set password for each file and folder under linux.
A good post nixcraft, but I have a doubt, how linux encrypts? I mean in a navite level, without use particular apps or tools… thx
Non interactive encrypt/decrypt:-
Encrypt it…
gpg –yes –passphrase [passphrase] -c [filename]
Decrypt it…
gpg –yes –passphrase [passphrase] [filename]
Piece of pie…