You can sign, encrypt, and decrypt your private email and send a signed and encrypted email to a sender using GPG. Both the sender and the recipient of the email should create their own key pair and import each other’s public key in each of their keyrings for that purpose.

Let’s discuss how to sign and encrypt emails using GPG.

Setup:

•  Install Thunderbird for your OS.
• Set up your Thunderbird email account for your email id.
•  Install Enigmail, which is an add-on for Thunderbird.
• Go to Settings for your Thunderbird email account. Click on OpenPGP Security. Enable PGP.
• Select the key-id for your key to use it for encryption and decryption.
• Specify whether you want to sign and encrypt messages by default.

How to send someone a signed and encrypted email using GPG?

• Now, go to the Write Message option. Type the sender, who has your public key in her keyring, and type the message.
• It will ask your passphrase while sending out the email.
• You are done.

How to read an email encrypted with GPG?

• Click on the email.
• It will ask for your passphrase. Give your passphrase.
• If you imported the sender’s public key on your keyring, the email will decrypt automatically.

I hope this helps. Interested readers who want to know more about how different cryptographic algorithms and Public Key Infrastructure work may want to refer to the book “Cryptography And Public Key Infrastructure.”