From: Antoine Leca (Antoine10646@leca-marti.org)
Date: Fri Dec 03 2004 - 08:26:18 CST
On Friday, December 03, 2004 13:10, Cristian Secarã va escriure:
>
> However, the .ttf fonts that ship with their products are showing an
> OT icon. I don't know how it's done technically.
Technically, it is done by including a (valid) 'DSIG' (digital signature)
subtable into the font file, that is a table whose only aim is to guarantee
that the fontfile has been unaltered (using cryptographic seals as used for
certificated e-mails).
The interesting thing is that while the specification for this 'DSIG' table
is part of OpenType, it is completely unrelated to what people usually
associates with this technology, that is the possibility to have complex
script and advanced typography support (see my previous post for details,
since I did the mistake myself ;-).) Neither it is related to the fact (also
introduced by the OpenType specifications) to have the outlines and hints
stored in Postscript format (rather than the traditional TrueType format)
As a result, having the nice-looking OT on a font is misleading, it just
means the designer have paid Verisign for a class 3 certificate and signed
its font. And last but not least it ensures you the font has not been
modified (I am hoping Windows is actually checking the seal, but when I
thought a bit more I am not 100% sure, since this is a process that is
somewhat time-consuming, and it does not appear to me that Windows is less
quick to draw the content of this folder...)
Antoine
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