[pdftex] pdfcrypt

[Hans Hagen]

At 04:02 PM 10/4/2002 +0200, Thierry Bouche wrote:

>Given that pdftex contains primitives that almost none of his users are
>aware of, I find it surprizing that the crypting code be eventually
>removed, as it is desactivated by default, and will be usefull in some
>obvious cases.

The main reason for removing encryption is that it leads to nearly 
unmaintable code. This is due to the way pdftex is built on top of tex: 
change files (upon change files) and a mixture of pascal code and c code.

[another reason is that in some cases encryption of object content assumes 
knowledge of the kind of content and interpretation of object context is 
not something to leave up to pdftex; it may be doable by providing 
primitives that conyrol the encryption, but that assumes clever macro 
packages]

>batch, pdftex+pdfcrypt makes a corrupted file when used in a single run,
>pdftex+pdfcrypt does proper encryption when used as a postprocessor over

indeed, this was the main reason for the removal

>the previously assembled PDF file. But then linearization is
>unavailable. If this feature was not in sight, I must say that pdftex
>would have proven the most robust and versatile tool for cooking the
>delivered PDF files, as it preserves rigourously the data of each page
>included, which most other PDF utilities won't (pstill "optimization"
>will convert CCIT G4 pages to ZIP, doubling their size, most tools would
>destroy the hidden text, etc.). BTW, I also consider putting the hidden

a bit off topic, but it may be nice to know that ghostscript can downsample 
files while leaving annotations untouched, contrary to distiller; the 'keep 
things unchanged' aspect that you mention is indeed pretty important

>text from an alternative OCR with rich XML output format instead of the
>one I have, and for this too pdftex should be one of the rare available
>tools.

right!

Hans
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