GPG
How to generate and use GPG Keys.

Generate Key
gpg --full-generate-key 
 Select defaults or the required option if you have them 
 Select an expiration date 
 
 Enter your personal information (it needs to be consistent with your account info) 
 
 Use a secure passphrase 
 
 Key can be listed with: 
 gpg --list-secret-keys --keyid-format=long 
 Key can exported with: 
 gpg --armor --export <key> 
 
 Screenshots:

Add Keys to Github/Gitea
Github 
 
 Settings 
 SSH and GPG keys 
 New GPG Key 
 Paste in the public key block 
 Add GPG Key 
 Turn on Vigilant mode 
 
 
 Gitea 
 
 Settings 
 SSH / GPG Keys 
 Add Key 
 Paste in the public key block 
 Add Key 
 Verify 
 
 Screenshot:

Telling Git about your Key
gpg --list-secret-keys --keyid-format=long 
 git config --global user.signingkey <key> 
 Screenshot: