- From: Jonathan Kew <jonathan@jfkew.plus.com>
- Date: Thu, 10 Sep 2009 17:14:21 +0100
- To: John Hudson <tiro@tiro.com>
- Cc: www-font <www-font@w3.org>
On 10 Sep 2009, at 17:05, John Hudson wrote: > A quick question re. WOFF: > > When a WOFF format font is created, what happens with the dsig in > the original OT font. Is this preserved in some way? Is the DSIG > table compressed in the same manner as the other tables, and does it > remain verifiable in some way? It used to be that it was discarded (because the signature would no longer be valid), but the WOFF spec has now been tightened up such that if you encode a fully valid OpenType font (i.e., checksums are correct, tables properly padded, etc) and then decode it again, you get a binary-identical file back. And therefore the DSIG can be preserved and verified (by decompressing, and then proceeding as usual). If the original font has inconsistencies such as a bad checksum, then the encoder will fix this (with a warning) and discard the DSIG (also with a warning) because the signature would no longer match the data. Hope that clarifies it for you. JK
Received on Thursday, 10 September 2009 16:15:09 UTC