This gives me a verified iso:
cd /iso
wget 
https://mirror.alpix.eu/tails/tails/stable/tails-amd64-3.16/tails-amd64-3.16.iso
wget 
https://tails.boum.org/torrents/files/tails-amd64-3.16.iso.sig
wget 
https://tails.boum.org/tails-signing.key
gpg --import tails-signing.key
TZ=UTC gpg --no-options --keyid-format long --verify 
/iso/tails-amd64-3.16.iso.sig /iso/tails-amd64-3.16.iso
if [ $? -eq 0 ]
then
     yad  --width=220  --title "**Iso verified**" --text "Iso is 
verified"  --button="OK"
else
     yad  --width=220  --title "**Iso not verified**" --text "Iso is not 
verified"  --button="OK"
fi
On 2019-10-01 11:30, linux-service wrote:
 > More and more organisations prevent (and disable) usb and sd ports on
 > notebooks. So booting tails with usb is no option.
 >
 > Would this be good practice to use tails by booting the iso (on the
 > internal disk) with grub to ram. When tails is running, the present
 > harddisks are not mounted.
 >
 > so, Download official tails iso from the tails website, gpg verify the
 > iso and after this booting the iso with grub.
 >
 > for example with(warning, not working):
 >
 > wget
 > 
https://mirror.alpix.eu/tails/tails/stable/tails-amd64-3.16/tails-amd64-3.16.iso
 > wget https://tails.boum.org/torrents/files/tails-amd64-3.16.img.sig
 > wget https://tails.boum.org/tails-signing.key
 > gpg --import tails-signing.key
 > TZ=UTC gpg --no-options --keyid-format long --verify
 > /iso/tails-amd64-3.16.img.sig /iso/tails-amd64-3.16.iso
 > if [ $? -eq 0 ]
 > then
 >     yad  --width=220  --title "**Iso verified**" --text "Iso is
 > verified"  --button="OK"
 > else
 >     yad  --width=220  --title "**Iso not verified**" --text "Iso is not
 > verified"  --button="OK"
 > fi
 >