is there a safe marshaler?

[Irmen de Jong]

Paul Rubin wrote:

> Hmm, you also want a random blob in each packet (including the session
> start) included in the authentication of the next packet, so the
> attacker can't cut and paste messages from old sessions into the
> current ones.  You know, by the time you're through designing this you
> may be better off just using SSL and getting it over with.  It's very
> easy to make mistakes designing these types of protocols.  There are
> some reasonable examples in "Applied Cryptography", but maybe you
> don't want to deal with this stuff.

Heh, indeed I rather don't.
I know a bit about this stuff, but not nearly enough to come
up with a water tight design by myself, so it's much easier
and safer to rely on trusted work by others.


>>I label things like SOAP and XML-RPC much different than RMI or Pyro,
>>because they (SOAP) are much more "distant" from the actual
>>programming language and environment beneath them. I don't know if
>>this is good thinking or not but the fact that RMI and Pyro expose
>>language features directly, and SOAP not, makes that I reason about them
>>differently.
> 
> 
> Hmm, I sort of understand this, but not completely.  Does DCOM or .NET
> expose language features directly?

.NET: no idea
DCOM: as it is based on DCE/RPC, I would say: no. There's this MIDL
thing sitting in between and stuff like that. There's no such thing
as a specific class id and/or method name and/or parameter list that
directly maps onto an object.method in the programming environment.

I must confess, this stuff is getting all rather messy and probably not
worth to try to make such a distinction between all the RPC protocols :-)

> I've been meaning to look at Pyro and will certainly let you know if I
> spot any problems, but of course there might be some that I don't find.

I would appreciate it.


>>Furthermore there are practical issues such as having to
>>open a buch of new ports in your firewall. In my experience
>>this is very hard to get done, sadly, in contrast to just
>>exposing a "web-service" (in whatever form) on port 80 HTTP.
> 
> 
> Yes, though RMI requires the same.

Precisely. There is this tunneling thing, but I never got it to work.
In the end, using a SSH tunnel may prove to be even easier :-D
(just let sshd listen on port 80 and you're set)


--Irmen