Debian: ------- See: https://ftp-master.debian.org/keys.html gpg --no-options --trust-model always --no-default-keyring --secret-keyring /dev/null --keyring ./debian-.gpg --recv-keys Ubuntu: ------- get keys from installed system: apt-key list --fingerprint gpg --no-options --trust-model always --no-default-keyring --secret-keyring /dev/null --keyring ./ubuntu-archive.gpg --recv-keys Openwrt ------- See: https://openwrt.org/docs/guide-user/security/signatures gpg --no-options --trust-model always --no-default-keyring --secret-keyring /dev/null --keyring ./openwrt-.gpg --import < (follow download link)