Eu faço e obtenho
# http://stackoverflow.com/a/10260634/54964
root@masi:/home/masi/Documents# gpg --keyserver subkeys.pgp.net --recv-key 06F90DE5381BA480
gpg: directory '/root/.gnupg' created
gpg: new configuration file '/root/.gnupg/gpg.conf' created
gpg: WARNING: options in '/root/.gnupg/gpg.conf' are not yet active during this run
gpg: keyring '/root/.gnupg/secring.gpg' created
gpg: keyring '/root/.gnupg/pubring.gpg' created
gpg: requesting key 381BA480 from hkp server subkeys.pgp.net
?: subkeys.pgp.net: Network is unreachable
gpgkeys: HTTP fetch error 7: couldn't connect: Network is unreachable
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
Eu estou tentando mudar para backports R porque eu preciso de R 3.3.2, então eu já fiz a adição da seguinte linha em /etc/apt/sources.list
deb http://cran.wu.ac.at/bin/linux/debian jessie-cran3/
root@masi:/home/masi/Documents# gpg --keyserver keys.gnupg.net --recv-key 06F90DE5381BA480
gpg: requesting key 381BA480 from hkp server keys.gnupg.net
gpg: /root/.gnupg/trustdb.gpg: trustdb created
gpg: key 381BA480: public key "Johannes Ranke (CRAN Debian archive) <[email protected]>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg: imported: 1
root@masi:/home/masi/Documents# apt-get update
...
Fetched 116 kB in 3s (32.1 kB/s)
Reading package lists... Done
W: GPG error: http://cran.wu.ac.at jessie-cran3/ Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 06F90DE5381BA480
OS: Debian 8.5
Veja as instruções de instalação para os pacotes Debian no CRAN, seção Secure apt :
The Debian backports archives on CRAN are signed with the key of Johannes Ranke (CRAN Debian archive) with key fingerprint 6212 B7B7 931C 4BB1 6280 BA13 06F9 0DE5 381B A480. You can fetch and import this with
apt-key adv --keyserver keys.gnupg.net --recv-key 6212B7B7931C4BB16280BA1306F90DE5381BA480