this is failing for me on armv7 but not on amd64

able to reproduce it on amd64, so this appears inconsistent. possibly one bad mirror?

Or bad hard disk or cosmic ray... modified files in /etc are preserved because they are "configuration files" so the reinstallation will not overwrite the modified file on your system.

Try it with « apt-get -o options::dpkg::="--force-confask" --reinstall install debian-archive-keyring » and it will offer you to replace the file.

root@localhost:/# debsums -a debian-archive-keyring
/usr/share/doc/debian-archive-keyring/README OK
/usr/share/doc/debian-archive-keyring/changelog.gz OK
/usr/share/doc/debian-archive-keyring/copyright OK
/usr/share/keyrings/debian-archive-keyring.gpg OK
/usr/share/keyrings/debian-archive-removed-keys.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-jessie-security-automatic.gpg FAILED
/etc/apt/trusted.gpg.d/debian-archive-squeeze-stable.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-squeeze-automatic.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-jessie-stable.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-wheezy-stable.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-wheezy-automatic.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-jessie-automatic.gpg FAILED
root@localhost:/# apt-get clean
root@localhost:/# apt-get update
Get:1 http://security.kali.org kali/updates Release.gpg [819 B]
Get:2 http://http.kali.org kali Release.gpg [819 B]
Get:3 http://security.kali.org kali/updates Release [11.0 kB]
Get:4 http://http.kali.org kali Release [21.1 kB]
Get:5 http://security.kali.org kali/updates/main armhf Packages [342 kB]
Get:6 http://http.kali.org kali/main armhf Packages [7717 kB]
Ign http://security.kali.org kali/updates/contrib Translation-en
Ign http://security.kali.org kali/updates/main Translation-en
Ign http://security.kali.org kali/updates/non-free Translation-en
Ign http://http.kali.org kali/contrib Translation-en
Ign http://http.kali.org kali/main Translation-en
Ign http://http.kali.org kali/non-free Translation-en
Get:7 http://security.kali.org kali/updates/contrib armhf Packages [20 B]
Get:8 http://http.kali.org kali/non-free armhf Packages [87.2 kB]
Get:9 http://security.kali.org kali/updates/non-free armhf Packages [20 B]
Get:10 http://http.kali.org kali/contrib armhf Packages [42.2 kB]
Fetched 8223 kB in 14s (551 kB/s)
Reading package lists... Done
bian-archive-keyringt-get -o options::dpkg::="--force-confask" --reinstall install de
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
bundler python-impacket-doc
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 1 not upgraded.
Need to get 60.7 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://http.kali.org/kali/ kali/main debian-archive-keyring all 2014.3~deb7u1 [60.7 kB]
Fetched 60.7 kB in 10s (5671 B/s)
(Reading database ... 125610 files and directories currently installed.)
Preparing to replace debian-archive-keyring 2014.3~deb7u1 (using .../debian-archive-keyring_2014.3~deb7u1_all.deb) ...
Unpacking replacement debian-archive-keyring ...
root@localhost:/# debsums -a debian-archive-keyring
/usr/share/doc/debian-archive-keyring/README OK
/usr/share/doc/debian-archive-keyring/changelog.gz OK
/usr/share/doc/debian-archive-keyring/copyright OK
/usr/share/keyrings/debian-archive-keyring.gpg OK
/usr/share/keyrings/debian-archive-removed-keys.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-jessie-security-automatic.gpg FAILED
/etc/apt/trusted.gpg.d/debian-archive-squeeze-stable.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-squeeze-automatic.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-jessie-stable.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-wheezy-stable.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-wheezy-automatic.gpg OK
/etc/apt/trusted.gpg.d/debian-archive-jessie-automatic.gpg FAILED
root@localhost:/#

Those cosmic rays are amazing, keep corrupting the same files every time.

a little copy pasta on this line:

bian-archive-keyringt-get -o options::dpkg::="--force-confask" --reinstall install de

it should read "apt-get -o options::dpkg::="--force-confask" --reinstall install debian-archive-keyring" as you suggested, you can see from the lines after that the line was correct.

If you tried to document yourself on what I suggested to do, you would have noticed that I made a small mistake in the APT option, it should have been « apt-get -o dpkg::options::="--force-confask" --reinstall debian-archive-keyring ».

If dpkg isn't asking you if you want to update the broken files, then the syntax is not working... cf man dpkg and /usr/share/doc/apt/examples/apt.conf