Manually Archived keyrings can be installed - what about automatic?

[Rajib Bandopadhyay <bkpsusmitaa@gmail.com>]

[Kind attn] Prof. Noah Meyerhans

Dear List Subscribers,

I would like to draw your kind attention to my earlier post:
        Archived Debian releases without security site: lists.debian.org

Thanks to Prof. Meyerhans I was able to solve the issue, albeit manually.

How do I introduce appropriate lines in /etc/apt/sources.list, to
download archived keyrings, such as:
http://archive.debian.org/debian/pool/main/d/debian-archive-keyring/
	debian-archive-keyring_2010.08.28~lenny1_all.deb

so I could install the security keys automatically, instead of
manually downloading the keys individually and installing them from
the terminal? like the Package debian-archive-keyring from following

    squeeze (oldoldstable) (misc): GnuPG archive keys of the Debian archive
    2010.08.28+squeeze1: all
    wheezy (oldstable) (misc): GnuPG archive keys of the Debian archive
    2014.3~deb7u1: all
    jessie (stable) (misc): GnuPG archive keys of the Debian archive
    2014.3: all
    stretch (testing) (misc): GnuPG archive keys of the Debian archive
    2014.3: all
    sid (unstable) (misc): GnuPG archive keys of the Debian archive
    2014.3: all

Now, these Debian-security Keyrings can be downloaded from apt
directly by using:
    deb http://ftp.de.debian.org/debian [distribution name] main

So normal apt line is sufficient for downloading the security keyring.

Then what does this following line do in /etc/apt/sources.list :
deb http://security.debian.org stable/updates main contrib non-free ?

According to https://www.debian.org/security/   this line to use apt
to easily get the latest security updates.

According to the above line, we need not use the line:
deb http://security.debian.org/ lenny/updates main contrib non-free
for lenny since it is already archived and therefore, does not receive
any more security updates?

Hence, for archived Lenny, should I remove the line:
deb http://security.debian.org/ lenny/updates main contrib non-free
from /etc/apt/sources.list ?

Regards,
Rajib