[Cryptography] Two quick questions about IPsec AH

[Dan McDonald]

Taking snippets of Tero's response...

On Jan 11, 2022, at 2:44 AM, Tero Kivinen <kivinen at kivinen.iki.fi> wrote:
> 
> Most of them considered the end-to-end principle as sacred,
> meaning all packets originate from one end and are delivered through
> the network unmodified to the final destination.
> 
> Thus in a way IPsec was also evil as in most common usage of it, IPsec
> did break that end-to-end principle too. I.e., when having site to
> site VPNs or similar the end-to-end principle was broken, but it was
> not as evil as NATs as the damage done to the packets was undone on
> the other end...
> 
> Those end-to-end people did say that we need to run IPsec on every
> single device, i.e., we want to use host to host IPsec, instead of
> stei to site VPN...

... I was definitely this sort of person back throughout the entire 1990s.

I'd always imagined IPsec being a socket-option at the IPPROTO_IP layer when I read the first IPng Security Architecture documents. Once at Sun, people reminded me that not all apps could-or-would be recompiled, and so you needed some sort of per-machine (eventually per-netstack) configuration, hence the birth of Solaris/illumos ipsecconf(1M) and what got formalized as the SPD.

Oh, one more thing:

> If I remember correctly there was some corporate division issues with
> the microsoft windows IPsec team, i.e., the IPsec was NOT done on the
> people implementing network devices, but by the people implementing
> dialup etc stuff, thus it was only usable when using such
> configurations or something like that.

I can't speak for Microsoft, but such divisions happened in other large firms as well.  The people who wanted quick delivery of "secure networking" would do horrible things like the godawful bump-in-the-stack implementation. Such an implementation would wedge itself between IP and the network device, and often need to reimplement chunks of IP inside itself. While describing this to fellow Sun TCP/IP folks, Erik Nordmark correctly characterized that such implementations were identical to devices placed at an arbitrary point on the network, with all such middlebox properties.

Dan