Package: debian-live Version: 9.4.0 LiveCD (debian-live-9.4.0-amd64-mate.iso) don't contain dirmngr package, so gpg also don't work.
wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/SHA512SUMS wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/SHA512SUMS.sign gpg --verify SHA512SUMS.sign Result gpg: using RSA key DF9B9C49EAA9298432589D76DA87E80D6294BE9B gpg: Can't check signature: No public key. Ok, then I just get public key! gpg --recv-keys DF9B9C49EAA9298432589D76DA87E80D6294BE9B Result: gpg: failed to start the dirmngr ’/usr/bin/dirmngr’: No such file or directory Yes, yes, sudo apt-get install dirmngr. But I think this package must by installed by default.
