Paulo,

Paulo Soares-3 wrote:
> 
> iText is under some heavy changes:
> 
> - move to Java 5
> - generics and enums to improve type safety
> - more interfaces with the exterior and less concrete classes
> - signature code moved out of core iText and the use of a signature
> plug-in
> - default signature plug-in based on BouncyCastle, if you don't use 
> signatures there's no need to carry all the BC jars
> 
> Input is very much welcome in this thinking phase.
> 

Being back to work now, I'd be happy to give some input.

Due to the usage scenario I have to deal with here, I'm mostly into the
variants using externally created and verified signature containers.
Additionally PAdES features are in focus.

As you mention a "signature plug-in", are there already concrete plug-in
architecture ideas? Or is that more an abstract concept?

To separate the signature code from the core code, some additional formerly
hidden PDFStamper functionality must be made public (in some safe manner).

This is especially necessary when embedding signatures: When serializing the
dummy /ByteRange array and /Contents string, their start and end offset in
the file must be known to fill in the correct range data after serializing,
to read the range to sign, and eventually to fill in the generated signature
container. This could be implemented using listeners which are triggered for
objects when they are serialized.

As the representations of direct PDF objects might be referenced multiple
times, a listener registered with it may also be called multiple times.
Therefore, the listener must not only be given an offset range but also some
kind of path of the object, probably having the containing indirect object
as its root.

For safety reasons, the offset range should not be given as numeric values
but as some abstractions allowing to manipulate this range and only this
range. Additionally this abstraction should be type aware and only allow
manipulation in a correct manner.

At first glance this is the main change to the core code required for
separation.

Regards,   Michael.
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