[Tutorial for beginners] How to install and use GnuPG on GNU/Linux

Hello, friends!

​

If you are worried about your personal/professional documents and want to keep them safe, I'd like to recommend the software *"GnuPrivacy Guard"* (a.k.a *GnuPG* or *GPG*).

But, first things first. I don't want to be rude, but I am presuming that you have a GNU/Linux distribution installed into your computer, and that you have the basic knowledge on how to use your system, install a package using graphical and command line interface, how to use the terminal etc. I recommend to use Internet to learn about GNU/Linux before continue with this simple tutorial.

GnuPG is a software that complies with OpenPGP standard, modelled on a program called *Pretty Good Privacy* (*PGP*). PGP is a program written by Philip R. Zimmermann in 1991.

An additional information you need to know is that GPG needs 2 encryption keys for each user. They are: private key and public key. The private key is used to encrypt, while the other key, public key, is used to decrypt. Also, your keys are going to storage your name, your e-mail, a password and a comment that explains, in few words, the purpose of these keys.

Let's start with the software installation. Open a terminal and type this command:

For Debian/Ubuntu and Debian-based distributions

sudo apt install gnupg

For RedHat/Fedora and RedHat-based distributions

sudo yum install gnupg

Once installed, let's create and use your new keys. In a terminal, type:

gpg --full-generate-key
gpg --full-gen-key # Command with abbreviated/short parameter

https://i.redd.it/6agjpes16wg31.png

The first prompt wants to know which option you want. Let's select the option number 1, which is the default. You can press **ENTER** without type any value.

The next prompt asks for the key size. What is key size? In simple words, it's about the security level/force of your keys. You can pick the default option pressing **ENTER** or any other value between 1024 and 4096 bits.

https://i.redd.it/bu4pceq36wg31.png

Now, let's define for how long these GPG keys are going to be valid. Using the list bellow as a reference, you can choose days, weeks, months and years. My recommendation is 1 year. So, you can type: **365** **ENTER** (or) **1y** **ENTER**

https://i.redd.it/q128em756wg31.png

As soon as you pick an option, the following prompt asks to confirm. Type **Y** and press **ENTER.**

https://i.redd.it/63o6yj396wg31.png

The next step is to insert your personal information. In the last line (Change name, comment...), you can use uppercase or lowercase letters.

https://i.redd.it/egljr45b6wg31.png

This is one of the most important part of GPG keys creation: the password. It's extremely recommended to use a strong password. Strong passwords are passwords combining uppercase/lowercase letters, numbers and special characters, e.g.: Th1s\_1s\_@\_STr0nG\_P@ssW0rd

https://i.redd.it/s1o6eovd6wg31.png

As soon as you press "OK", GnuPG is going to take a moment to create your keys. Don't worry about the time, just wait. The last thing you are going to see is the following information.

https://i.redd.it/moe7ceo69wg31.png

Voilá! You created your keys.

Using the same terminal, you can list your keys:

gpg --list-key # You can use '--list-keys' in plural; the output is the same
gpg -k # Command with abbreviated/short parameter

https://i.redd.it/yntsp5ki6wg31.png

Now, let's start with the encryption and decryption steps of a file. In the terminal, create a simple TXT file:

echo "This is a secret message!" > example.txt
cat example.txt

https://i.redd.it/yaem8xqs6wg31.png

As you can see, a file with a message was created. You can open it with a simple notepad. To encrypt it, type:

gpg --recipient <YOUR_EMAIL> --encrypt example.txt
gpg -r <YOUR_EMAIL> -e example.txt # Command with abbreviated/short parameter

Once you press **ENTER**, the file **"example.txt"** will be encrypted as **"example.txt.gpg"**. If you try to read it using the command **"cat"**,

you are going to see strange characters in your screen.

cat example.txt.gpg

Another option is to encrypt all the information in a readable file. To do this, you must add the parameter `--armor` or `--armour` (sort version `-a`), and the output file will be **"example.txt.asc"** You can read it using the command **"cat"** or a simple notepad.

gpg --recipient <YOUR_EMAIL> --encrypt --armour example.txt
gpg --recipient <YOUR_EMAIL> --encrypt --armor example.txt
gpg -r <YOUR_EMAIL> -e -a example.txt # Command with abbreviated/short parameters

https://i.redd.it/vy35j36w6wg31.png

You learned how to encrypt, but how about the decrypt method? It's simple! You need to replace `--encrypt` or `-e` by `--decrypt` or `-d`, and add the parameter `--output` or `-o` followed by the filename. But there's a detail, the output parameter needs to come before the decrypt parameter. Also, it doesn't matter if you encrypted a file as *.GPG* or *.ASC*, the GnuPG is going to decrypt both. Before learn how to decrypt, I'd like to ask you to delete the file **"example.txt"** and keep any encrypted file (example.txt.gpg / example.txt.asc).

gpg --recipient <YOUR_EMAIL> --output example.txt --decrypt example.txt.gpg
gpg -r <YOUR_EMAIL> -o example.txt -d example.txt.gpg # Command with abbreviated/short parameters

In this moment, a password window is asking for your GnuPG password. Once you typed the correct password, your file is going to be decrypted.

https://i.redd.it/kc0zcio07wg31.png

Well... This is all, folks!

For more information about GnuPG, you can access the official website [GnuPG](https://gnupg.org)

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