Re: Question on DSIG and head flag 11

No, by "padding" I'm referring to the dead space between tables. This is
almost always 4-byte alignment by convention, but that isn't mandated by
any spec. So with the information currently plumbed through WOFF2 it would
be very easy to make a font that would fail DSIG validation.

Raph

On Mon, Jun 29, 2015 at 9:09 AM, Cosimo Lupo <cosimo.lupo@daltonmaag.com>
wrote:

> thanks for your reply, Raph.
> I imagine the 'padding' you are referring to is within the glyf table'
> glyph entries, so as such it shouldn't concern CFF fonts. The padding
> between sfnt tables or between data blocks inside WOFF2 is not optional.
> I'm afraid I don't know what you mean by other 'subtle details'.
>
> As far as I understand this, the only change required would be to ensure
> the original CFF font's table order is kept when encoding it to WOFF2, by
> simply saying that the WOFF2 table order (i.e. same as the WOFF2 directory
> order) is a trace of the table order in the original CFF font; and that
> this same table order should apply upon decoding (here I mean the offsets
> to the table data, not the order of directory entries which in sfnt must be
> sorted alphabetically).
>
> I know that DSIG is not currently checked for webfonts, and some may well
> see it as a waste of bytes. Fair enough.
>
> It just believe that if an encoder/decoder manages to not invalidate a
> digital signature, whenever it can, then it's doing its job well.
>
> Anyway, I don't want to push this too much. As I said, it was Chris Lilley
> who asked me to reopen the issue here.
>
> Thanks again,
>
> All best
>
> --
> Cosimo
>