Generating IDs for pdf files opened by pdf js

[Apurva Jalit]

Hello folks,
I am working on a browser extension that internally uses pdfjs to open pdf
documents on the browser. For a certain use case I need to get the ID of
the pdf opened by pdf js. I see this ID/URN or the identifier string for
the pdf printed in the console(when using pdf viewer extension to open a
pdf via pdfjs). For eg. for the page
http://www.ifets.info/journals/10_4/9.pdf I can see this string
"30eb7fcbb6756e461176fbbd0ceba7b9" in the console.

How is this ID generated? Is there a standard algorithm for it?

Thanks,
Apurva Jalit

[ydel...@mozilla.com]

On Tuesday, August 4, 2015 at 7:43:30 AM UTC-5, Apurva Jalit wrote:
> For a certain use case I need to get the ID of
> the pdf opened by pdf js. I see this ID/URN or the identifier string for
> the pdf printed in the console(when using pdf viewer extension to open a
> pdf via pdfjs).

> How is this ID generated? Is there a standard algorithm for it?

Hello,

A PDF file contains ID field that suppose to be somewhat unique, see the section 14.4. File Identifiers of the spec [1]. If the ID field in absent or set to zeros, we calculate MD5 of the first 1024 bytes of the PDF file [2].

Thanks.

[1] http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/PDF32000_2008.pdf#page=559
[2] https://github.com/mozilla/pdf.js/blob/master/src/core/core.js#L512

[Randall Leeds]

Yes, it's in the PDF spec, which is a very long document so I can't dig up
the link right now.

It's two parts. It's a hash of some content, if I recall correctly, and
this is repeated. When the document is edited, one half is kept the same
and the other is recomputed. In this way, it's half fixed, half
version-related.

I don't think PDF.js calculates these. It just reads what's stored in the
PDF.

On Tue, Aug 4, 2015, 05:43 Apurva Jalit <apurva...@gmail.com> wrote:

> Hello folks,
> I am working on a browser extension that internally uses pdfjs to open pdf

> documents on the browser. For a certain use case I need to get the ID of

> the pdf opened by pdf js. I see this ID/URN or the identifier string for
> the pdf printed in the console(when using pdf viewer extension to open a

> pdf via pdfjs). For eg. for the page
> http://www.ifets.info/journals/10_4/9.pdf I can see this string
> "30eb7fcbb6756e461176fbbd0ceba7b9" in the console.
>

> How is this ID generated? Is there a standard algorithm for it?
>

> Thanks,
> Apurva Jalit
> _______________________________________________
> dev-pdf-js mailing list
> dev-p...@lists.mozilla.org
> https://lists.mozilla.org/listinfo/dev-pdf-js
>