PGP Encryption

I would love to use Bob and Alice for this article, unfortunately Bob’s name is too short. It needs a minimum length of 5 characters. To install GnuPG run

# macOS
brew install gnupg
# Ubuntu
sudo apt install gnupg

First you’ll need to generate the key.

gpg --gen-key

Enter your passphrase

And then reenter the same passphrase

Key generated successfully

To check if your keys are generated successfully

gpg --list-keys

Generate a ASCII armored version of the public key.

gpg --output kevin_public.key --export --armor kevin

Now that you have the public key. You can distribute this public key to anyone that wish to send you an encrypted file. The person that received your public key needs to import it into their key list.

gpg --import kevin_public.key

To list all the public keys

gpg --list-public-keys

To trust the public key

gpg --edit-key kevin

To encrypt

# --encrypt = to encrypt the file
# --armor = output encrypted file as ASCII
# --recipient = the imported public key uid
gpg --encrypt --armor --recipient kevin plain.txt
# or
gpg -e -a -r kevin plain.txt
# or
gpg -ear kevin plain.txt

By default the encrypted file output is a binary file

You need to have a secret/private key to sign the encrypted file

gpg --list-secret-keys

To sign and encrypt

gpg --encrypt --armor --sign --recipient kevin plain.txt
# or
gpg -easr kevin plain.txt

To decrypt

gpg --decrypt plain.txt.asc

Decrypting a signed encrypted file

Decrypting an encrypted file without signature

To delete key from the list of keys. First list all the keys

gpg --list-keys

To delete key “alice”

gpg --delete-key alice

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