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Linux Command Line: gpg

written by: jlwallen•edited by: J. F. Amprimoz•updated: 12/23/2008

GPG is the open source alternative to PGP. GPG and PGP are cryptographic software packages that encrypt and decrypt files to ensure security on a computer. In this entry to the Brighthub Linux Command Line series you will learn the basics of encrypting a file with GPG.

  • slide 1 of 3

    Generating a key

    Before you can do anything with GPG you need to generate a passkey. This key will allow you to encrypt and decrypt files. To generate your key enter the command:

    gpg --gen-key

    You will be asked a few questions during this process. The first question is:

    Please select what kind of key you want:

    (1) DSA and Elgamal -This is the default option.

  • slide 2 of 3

    Basic Usage

    I am going to assume that GPG is already installed on your computer.

    With that in mind, let's take a look the commands you need to encrypt and decrypt any file using GPG. To encrypt a file the command structure is;

    gpg [OPTIONS] recipient filename

    For simplicity I am going to show you how to encrypt a file for your own personal use. This means that only you, or anyone who has your personal gpg keyphrase working on your machine, can un-encrypt the file.

    In this case the recipient name will be your personal username you use on your Linux machine. So the actual comand to encrypt a file will be:

    gpg --encrypt --recipient 'USERNAME' filename

    This will create a new file called filename .gpg

    To decrypt the file use the command:

    gpg --output filename --decrypt filename.gpg

    When you encrypt a file you will not be asked for your passphrase.

    When you decrypt a file you will be asked for the passphrase used when you create your key.

  • slide 3 of 3

    Final Thoughts

    GPG is an outstanding tool to aid in your quest for a highly secure computer experience. But don't limit your gpg experience to encrypting files. You can expand gpg for email encryption and other types of encryption. There are thunderbird extensions that allow you to integrate gpg for simple email encryption. GPG is very flexible and very powerful. Get to know gpg and the many things it can do for you.

Keep your Linux box secure with these tools

Linux is well known for its security. It's one of the many reasons why IT managers insist on using Linux to keep data safe. But do you know the tools to keep your Linux boxes security as high as possible? This Bright Linux Commands series will introduce you to the tools you need to keep Linux secure
  1. Know your Linux security tools
  2. Linux Command Line: ssh
  3. Linux Command Line: gpg
  4. Let IPtables Help Secure Your Linux Box
  5. Linux Firewalls Made Easy With Fwbuilder