How to Generate Enough ‘Entropy’ For GPG Key Generation Process

The other I was trying to generate GPG key. It took really a long time and I was running out of time and losing my patience. The GPG isn't generated even after I waited for almost an hour. I am not aware of GPG key generation process at that time, and I have never created one before. So I dig a little in Google and found out that I need to generate enough Entropy for GPG key generation process. If you are ever been in this situation, read on. It was not that difficult.

Generate Enough 'Entropy' For GPG Key Generation Process

I entered the following command to create a GPG key:

$ gpg --gen-key

And, I got this message:

[...]
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
gpg: agent_genkey failed: No pinentry
Key generation failed: No pinentry

Key generation failed: No pinentry

As you in the above command, it shows there is "no Pinentry" package.

Make sure you have installed pinentry-gtk or pinentry-qt packages.

To install this package on Arch based systems, run:

$ sudo pacman -S pinentry

On RPM based systems:

$ sudo yum install pinentry

On DEB based systems:

$ sudo apt-get install pinentry

Then, create or edit gpg-agent.conf file:

$ sudo nano ~/.gnupg/gpg-agent.conf

And add one of the following lines:

pinentry-program /usr/bin/pinentry-curses

Or,

pinentry-program /usr/bin/pinentry-qt

Save and close the file. Reboot your system to apply the changes.

Now, let us create GPG key:

$ gpg --gen-key

Here is where I got struck for hours. I ran this command and waited for an hour. It says I don't have sufficient Entropy and didn't create the key.

To create enough entropy we need to install a package called "rng-tools".

On Arch Linux and its derivatives, run:

$ sudo pacman -S rng-tools

On RHEL and its derivatives, run:

$ sudo yum install epel-release

$ sudo yum install rng-tools

On Debian/Ubuntu and derivatives, run:

$ sudo apt-get install rng-tools

In case the above package is not available, try to install "rng-utils" instead.

After you installed this utility, run the following command to gain enough Entropy:

$ sudo rngd -r /dev/urandom

Repeat the above command until you got enough Entropy to create a GPG key.

Let us check the amount of bytes of entropy currently available using command:

$ cat /proc/sys/kernel/random/entropy_avail

Sample output:

3103

Now, try to create GPG key again. This time the GPG key generation process will be much faster.

$ gpg --gen-key

Enter your name and mail ID and press enter.

Enter your passphrase:

Re-enter passphrase:

Success! The GPG key has been created.

Hope this helps.