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GPG encryption commands ​

Create ​

The simple command

sh
gpg --gen-key

or the more advanced

sh
gpg --full-generate-key

Output will be something like this:

bash
pub   rsa3072 2019-08-20 [SC] [expires: 2021-08-19]
      XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
      XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
uid                      Me Xxxxxxx <mexxxxxxxxx@gmail.com>
sub   rsa3072 2019-08-20 [E] [expires: 2021-08-19]

Delete ​

sh
gpg --delete-secret-and-public-keys mexxxxxxxxx@gmail.com

Export ​

Public key:
to be sent to your friends so they can encrypt messages only you can decrypt

sh
gpg --armor --output xxxxxxx.public.gpg --export mexxxxxxxxx@gmail.com

Private key (only for backup)

sh
gpg --armor --output xxxxxxx.secret.gpg --export-secret-keys mexxxxxxxxx@gmail.com

Import ​

import public key from a friend

sh
gpg --import friendxxx.public.gpg

Edit trust level on an imported key from a friend ​

get keyid from --list-keys

sh
gpg --edit-key 9A5704E6742C5B32395057FCACB6EE444EE8C7A2 trust
# then select level of trust
gpg> 4

output:

bash
pub  rsa3072/ACB6EE444EE8C7A2
     created: 2021-02-05  expires: 2023-02-05  usage: SC
     trust: full          validity: full
sub  rsa3072/6634A7A0E2024ADE
     created: 2021-02-05  expires: 2023-02-05  usage: E
[  full  ] (1). My Friend

Then save and quit:

sh
gpg> save

Sign an imported key from a friend (validity) ​

sh
gpg --lsign-key 9A5704E6742C5B32395057FCACB6EE444EE8C7A2

Encrypt ​

Using public key of your friend:

sh
gpg --output file.txt.gpg --encrypt --recipient friendxxx@gmail.com file.txt

Add signature ​

To verify you're the sender

sh
sha256sum file.txt | awk '{print $1}' > file.txt.sha256sum
gpg --output file.txt.sha256sum.sig --sign file.txt.sha256sum

Decrypt ​

Decrypt encrypted files sent to you:

sh
gpg --output decrypted.txt --decrypt file.txt.gpg

Verify signature ​

Verify that your friend created the message

sh
gpg --verify file.txt.sha256sum.sig