Comments on visible signature profile

[Juan Carlos Cruellas <cruellas@ac.upc.edu>]

Hi,

Below follow some comments related to the visible signature profile. 
They are on Committee Specification v01 of 8 May 2010

Line 57:  "is related to the binary digital signature". I would propose 
to get rid of "binary" and leave "digital signature" only (this may be a 
CMS or a XML or even a PDF signature)....

Line 63: This is the first place where the term "visible Signatures" 
appears, without any definition. Befor that line  other terms have been 
used "visible information" (of the signature), "displayed 
information"...I am not sure about the usage of this term...in fact, the 
Part 6 of PAdES, which I would say could be strongly related to our 
profile has as title: "Visual Representations of Electronic Signatures". 
In its scope it defines:

. Signature appearance: visual representation of the human act of 
signing placed within a PDF document at signing time and linked to an 
advanced electronic signature

. Signature verification representation: visual representation of the 
verification of an advanced electronic signature.

Link to part 6 of PAdES:
http://etsi.org/deliver/etsi_ts/102700_102799/10277806/01.01.01_60/ts_10277806v010101p.pdf

I would propose to consider the possibility of changing of hte term 
"visible signatures" for a term more accurate to what we mean, i.e., a 
visual representation of the signature...

. Line 92: apparently another term "visible content"

. Lines 96 to 98:  In the first line I read: "..the document already 
contain visible signature placeholders (named "signature fields")...", 
so this to me means that signature fields are fields for the visual 
representation of a signature....Then lines 97 to 98 read: "As part of 
the digital signature operation, the client will need to specify which 
signature field should be signed"...this to me means that some of the 
fields where the visual information will appear will actually be signed, 
and others no...but the key issue is that the term "signature field" is 
not a field where the digital signature goes, but the field where a 
visual representation of a digital signature appears....am I correct? 
and if so, wouldn't a change in the naming be worth?

. Line 266 to 276. FieldName...I copy the wording of the two first lines:
"This optional input will define the identitiy of a signature field to 
be signed. This parameter will be sent when it is required to 
incorporate a visible signature into the given field."

So the text seems to indicate that this field first identify the field 
to be signed (?) and second the field where the visual representation of 
the signature will be included... so, this seems to indicate that the 
visual representation has to be included in the field, and that this 
field must be signed....am I right?


Line 579. FieldName for optional input for verification. The spec reads 
that it  "willd efine the identitiy of a signature field to be 
verified"...what exactly validating only one field means?...and what is 
its relationship with the validation of a signgature?

Regards

Juan Carlos.