Portage rsync tree verification

Title: Portage rsync tree verification
Author: Michał Górny <mgorny@gentoo.org>
Posted: 2018-01-30
Revision: 1
News-Item-Format: 2.0
Display-If-Installed: <sys-apps/portage-2.3.62

Starting with sys-apps/portage-2.3.21, Portage will verify the Gentoo
repository after rsync by default.

The new verification is intended for users who are syncing via rsync.
Users syncing via git or other methods are not affected, and complete
verification for them will be provided in the future.

The verification is implemented via app-portage/gemato. Currently,
the whole repository is verified after syncing. On systems with slow
hard drives, this could take around 2 minutes. If you wish to disable
it, you can disable the 'rsync-verify' USE flag on sys-apps/portage
or set 'sync-rsync-verify-metamanifest = no' in your repos.conf.

Please note that the verification currently does not prevent Portage
from using the repository after syncing. If 'emerge --sync' fails,
do not install any packages and retry syncing. In case of prolonged
or frequent verification failures, please make sure to report a bug
including the failing mirror addresses (found in emerge.log).

The verification uses information from the binary keyring provided
by the app-crypt/gentoo-keys package. The keys are refreshed
from the keyserver before every use in order to check for revocation.
The post-sync verification ensures that the authenticity of the key
package itself is verified. However, manual verification is required
before the first use.

On Gentoo installations created using installation media that included
portage-2.3.22, the keys will already be covered by the installation
media signatures. On existing installations, you need to manually
compare the primary key fingerprint (reported by gemato on every sync)
against the official Gentoo keys [1]. An example gemato output is:

  INFO:root:Valid OpenPGP signature found:
  INFO:root:- primary key: 1234567890ABCDEF1234567890ABCDEF12345678
  INFO:root:- subkey: FEDCBA0987654321FEDCBA0987654321FEDCBA09

Please note that the above snippet does not include the real key id
on purpose. The primary key actually printed by gemato must match
the 'Gentoo Portage Snapshot Signing Key' on the website. Please make
sure to also check the certificate used for the secure connection
to the site!