Install GnuPG:

    $ doas pkg_add -v gnupg
    quirks-4.54 signed on 2022-01-09T19:08:35Z
    gnupg-2.2.30p0:npth-1.6: ok
    gnupg-2.2.30p0:libassuan-2.5.5: ok
    gnupg-2.2.30p0:libtasn1-4.17.0: ok
    gnupg-2.2.30p0:p11-kit-0.24.0: ok
    gnupg-2.2.30p0:libunistring-0.9.7: ok
    gnupg-2.2.30p0:libidn2-2.3.0p0: ok
    gnupg-2.2.30p0:libunbound-1.13.2: ok
    gnupg-2.2.30p0:gmp-6.2.1p0: ok
    gnupg-2.2.30p0:libnettle-3.7.3: ok
    gnupg-2.2.30p0:gnutls-3.7.2: ok
    gnupg-2.2.30p0:libksba-1.6.0: ok
    gnupg-2.2.30p0:libsecret-0.20.4: ok
    gnupg-2.2.30p0:pinentry-1.1.1: ok
    gnupg-2.2.30p0:libusb1-1.0.23p2: ok
    gnupg-2.2.30p0: ok


Create new key:

    $ gpg --generate-key
    $ gpg --full-gen-key (with dialog)


Export your private key (need be safety saved):

    $ gpg --export -a "baytuch@ircnow.org" > public.key
    $ gpg --export-secret-keys -a "baytuch@ircnow.org" > privat.key


List signatures:

    $ gpg --list-signatures


Send key to keyserver:

    $ gpg --keyserver keyserver.ubuntu.com --send-keys DD88244CA9988FAB


Search keys on the server:

    $ gpg --keyserver keyserver.ubuntu.com --search-keys "baytuch@ircnow.org"


Receive key:

    $ gpg --keyserver keyserver.ubuntu.com --recv-keys DD88244CA9988FAB


Sign your file:

    $ gpg --detach-sign photo.png


Verify your file:

    $ gpg --verify photo.png.sig


Crypt your file:

    $ gpg --encrypt --armor -o letter.asc letter.txt


Decrypt your file:

    $ gpg --decrypt -o letter_incom.txt letter_incom.asc