I wanted to install the Let’s Encrypt certbot package on a Raspbian Jessie installation that hosts my Asterisk PBX. I had manually installed a certificate but decided that the automated certificate installation is advantageous. Certbot is available as a backport.
Step 1 — Add the backport source location:
# echo "deb http://ftp.debian.org/debian jessie-backports main" \
> /etc/apt/sources.list.d/backports.list
Step 2 — # apt-get update
I received the following error:
W: GPG error: http://ftp.debian.org jessie-backports InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010
Step 3 — The two bolded keys needed to be added to the gpg keyring:
# gpg --keyserver pgpkeys.mit.edu --recv-key 8B48AD6246925553
gpg: requesting key 46925553 from hkp server pgpkeys.mit.edu
gpg: key 46925553: public key “Debian Archive Automatic Signing Key (7.0/wheezy)
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
# gpg -a --export 8B48AD6246925553 | sudo apt-key add -
OK
# gpg --keyserver pgpkeys.mit.edu --recv-key 7638D0442B90D010
gpg: requesting key 2B90D010 from hkp server pgpkeys.mit.edu
gpg: key 2B90D010: public key “Debian Archive Automatic Signing Key (8/jessie)
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
# gpg -a --export 7638D0442B90D010 | sudo apt-key add -
OK
Step 4 — Update the package list:
# apt-get update
Step 5 — Install the backported package:
# apt-get install certbot -t jessie-backports