Re: [Aglets-developer] signed aglets question

[Thomas H. <Tho...@es...>]

Dear Abdul-Gabbar,

On Thursday 09 March 2006 14:07, Abdul-Gabbar T. Al-Tamimi wrote:
> If I need an aglet to travel through a network with its signature.
> Firstly, it is included in a jar file, then the jar file will be
> signed. How to create and dispatch this aglet included in a jar
> file ???

I assume you use Tahiti as interface of the aglets server. Most of the 
job of creating and dispatching an aglet stored in a JAR is identical 
to working with one of the example aglets. The difference is that you 
need to provide in the 'Create Aglet' dialog the path to the JAR file 
in the 'Source URL' field, like this:
file:///home/user/myAglet/signedAglet.jar

I don't know exactly how the path would look like for Windows. Maybe 
if you put the JAR in the 'public/' directory of aglets you can write 
the Source URL in a different way, too. If you use restricted aglet 
permissions, you need to adapt the codeBase given in the policy file 
to the URL given in the 'Source URL'.

When the aglet is dispatched, I think the whole JAR is sent to the 
destination, but I am not sure.

Verifying the signature at the destination may not be straightforward. 
There was a related question a while ago about accessing an aglet's 
bytecode at the receiver. I don't remember he question getting an 
answers explaining how it can be done. There were only a few 
suggestions, that with the current server code the aglet will not be 
able to verify its own integrity, so the server will need to be 
changed.

If you want to retrieve the thread, surf to the aglets page in the 
sourceforge site, go to the mail section, from there to the archive 
of the aglet-users mailing list and there search for 'aglet bytecode' 
requiring all words of the query.

> Does there any other way to associate a signature with the aglet
> during its roaming ?

I can think of two ways:
- compute the signature offline, save it in a file, let the aglet read 
its own signature from the file, then send it roaming
- write a launcher aglet that calculates the signature of the worker 
aglet, then creates the worker aglet with the create(...) method of 
AgletContext and provides an object containing the signature as the 
'init' parameter

There are lots of details to get right, good luck!

Since part of your question is about using the aglets server, I have 
copied in the aglets-users mailing list, too.

It would be nice for you to provide a "Subject" for your messages 
towards the list, to make it easier to find back your question and 
its answers in the future. The words "aglet bytecode" I gave you 
above for finding the thread are taken from the Subject of those 
messages. :)

Hope this helps,
Thomas.
-- 
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