Ensuring that calling assembly signed by certain keys

8 Sep 2005 1:52 PM

Andy

Hi all,

I have a few questions about restricting who may call an assembly i'm
building.

First, I have a business assembly on a web server, with Serializable
objects that use remoting to move themselves to a data server (which
also has a copy of the business layer, and a data layer assembly as
well). Assuming this assembly is strongly named, do i need to worry
about someone comprimising the web server, decompling my business
assembly and then making calls via remoting to the data server? I know
the public key token is part of the version number of the assembly, but
i've also heard that the token itself could be applied to a rogue
assembly?

Second, is it possible to force that a caller of my assembly be signed
with certain public keys? Would adding such a restriction work, or
would it be too easy to fake a public key (from a dotnet or com
assembly)?

Thanks
Andy

10 Sep 2005 1:12 PM

Nicole Calinoiu

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"Andy" <ajohnst***@capcitypress.com> wrote in message
news:1126187535.243352.101620@g47g2000cwa.googlegroups.com...
> Hi all,
>
> I have a few questions about restricting who may call an assembly i'm
> building.
>
> First, I have a business assembly on a web server, with Serializable
> objects that use remoting to move themselves to a data server (which
> also has a copy of the business layer, and a data layer assembly as
> well). Assuming this assembly is strongly named, do i need to worry
> about someone comprimising the web server, decompling my business
> assembly and then making calls via remoting to the data server? I know
> the public key token is part of the version number of the assembly, but
> i've also heard that the token itself could be applied to a rogue
> assembly?

Any sort of code signing is essentially useless for identifying calling code
in a remoting scenario. See the thread at
http://groups.google.com/group/microsoft.public.dotnet.security/browse_frm/thread/ffbba47b0422fa94/
for a previous discussion of the same topic.

> Second, is it possible to force that a caller of my assembly be signed
> with certain public keys? Would adding such a restriction work, or
> would it be too easy to fake a public key (from a dotnet or com
> assembly)?

How easy it might be to fake or bypass such a protection depends very much
on the runtime environment. Is this still for the remoting scenario, or did
you have some other runtime scenario in mind for this question?