pickle/marshal internal format 'life expectancy'/backward compatibility

[Adam DePrince]

On Sun, 2005-02-06 at 12:12, Philippe C. Martin wrote:
> > How complicated is your data structure?  Might you just store:
> 
> that's the thing: I don't want to know: My goal is to be able to design

You must know.  Marshal and pickle both have limits on what they can
serialize.  

> my SC applications without having to change the file system every time I
> wish to add/subtract data to be store - I should say 'constant' data to be
> stored for this pickle solution would only work with data that the SC
> application just stores but does not understand/nor needs to.
> For instance, the data structure could simple have a name and address to
> start with (when the cards get issued) then the customer might want to add
> the person's pictures. In such a case, I would not have to release a new
> smart card application (could be burned in the silicon) but simply load
> the new structure at issuance time.

I don't see the problem.  What I proposed was merely a different way of
serializing your data.  The purpose of my simple signing scheme was not
to replace whatever services might be offered by the card, but to make
sure that the data you are reading into your python application was
written by you as a hedge against malicious data.   Can I, as a user of
said card, change the data in the pickle?  If so, when you load the
pickle back into python you need to confirm that it is a sane pickle
that you wrote earlier.  

- Adam

Adam DePrince