Integration with other portals and SharePoint: need help with a trust model

[Toynbee]

We have a government SharePoint portal that members authenticate and
authorize prior to viewing content.
A certain content (not all, only a small fraction) is to be shared
with OTHER (external) portals (those OTHER could be based on several
platforms, e.g. Websphere). That is, when users login to the OTHER
portals, they should be able to securely access a specific content on
OUR SharePoint portal, without having to authenticate/authorize at a
user specific level.
There is no AD or other trust relationship between those OTHER
portal / user directories and our directories.
We do not want to set up local user directories on our site. We do not
need to give access to content based on specific user profiles, anyone
who is authorized on those portals should be able to access this
information.
They can trust our site to show up on their portals, and we need to
somehow trust the users of those OTHER portals. Is there a lightweight
solution WITHOUT having to use heavyweight methods like just in time
assertions, XACML, SAML, installing certificates, etc. The easiest
would be for our SharePoint portal to trust any browser redirection
from their portals (say 5 of them), but that is probably too crude and
could be easily spoofed.
Is there a better / more robust solution?

[Steve]

Given your specifications, the only access method left that I see is
anonymous, and I doubt if you want that.

Have you considered accessing SharePoint content through Web Services from
your other portals? At least this way you would only have to deal with one
authentication account, although you would have to repeat this for each
external portal application.

HTH

"Toynbee" <ybhatt...@gmail.com> wrote in message
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