Re: [xml] Question about memory constraints when using SAX parser

[Veiko Sinivee <veiko sinivee solo delfi ee>]

Yes, I know about Aleksey's library. My library (libdigidoc) does
approximately the same but is more concerned with XAdES (ETSI TS 901103)
standard. XAdES is an add-on standard to XML-DSIG and defines additional
signature atributes. XAdES is supposed to be the European standard. 
I'm not quite
sure, but last time I looked I got the impression that Alesey's 
library handled only pure XML-DSIG. Also I think Aleksey's library uses
DOM parser. I use SAX (and I've had quite a headache because of this...)
but there are some customers who want to sign, verify, encrypt and
decrypt huge documents. For example some use this library to encrypt
database backups. I tested that it can encrypt an 800 MB file in
something like 2 minutes (P4, 2,4 GHz, 512 MB RAM). So there are uses
for both librarys. This one can be downloaded from
http://www.sourceforge.net/projects/gdigidoc. There you'll find
the library, a GTK-- userinterface (gdigidoc) and some smartcard
infrastructure modules (developed by other folks but packaged by me
because my program needs them). Ohh, yes the use of smartcards and
PKCS#11 is another case for my library. Offcourse Aleksey's library is
a fine pice of software. I've often looked at it to find out how he
does it and compare the results.

Veiko


Ãhel kenal pÃeval (esmaspÃev, 22. november 2004, 12:50+0100), kirjutas
Stefan Kost:
> Isn't there already Aleksey Sanins xmlsec lib at:
> http://www.aleksey.com/xmlsec/
>
> Stefan
>
> Veiko Sinivee wrote:
> > Hi,
> >
> > I'm writing a digital signature and xml encryption library. I want
> > to support encryption & decryption of very large files too. Well
> > encryption goes fine because I read, encrypt, base64 encode and write
> > data to the file in blocks of 8 KB or so. For decryption I choose to use
> > the SAX interface because it's probably the fastest and requires the 
> > least amount of memory. Now I found, that xmlCharaters() callback
> > function is still called with a lot of data. Earlier versions of libxml2
> > used to return data in blocks of x KB. Now If I have something like:
> >
> > <CipherData>
> > ...
> > 700 MB of base64 encoded data here
> > ...
> > </CipherData
> >
> > then the parser attempts to collect all of that data and return it
> > in one event to my callback function. This obviously doesn't work.
> > How can I switch it out and tell the parser to return at most x KB
> > in any event ?
> >
> > regards,
> >
> > Veiko Sinivee
> >
> > _______________________________________________
> > xml mailing list, project page  http://xmlsoft.org/
> > xml gnome org
> > http://mail.gnome.org/mailman/listinfo/xml
>
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