Hans,
I have the following sample:
\setupinteraction[state=start]
\starttext
\startTEXpage[offset=1em]
\definefield[x][signature]
\field[x]
\stopTEXpage
\stoptext
I can only use Acrobat to sign PDF documents with signature fields
generated by ConTeXt. Other tools sign the PDF document not producing a
valid signature (Acrobat cannot read or validate it).
From the source, signature has two objects (copied from the sample above):
2 0 obj
<<
/DA (/rmtf 11.9552 Tf 1.1955 Ts 0 0 0 rg 0 0 0 RG)
/DV <FEFF>
/F 4
/FT /Sig
/Ff 0
/Kids 1 0 R
/MaxLen 1024
/Q 0
/Subtype /Widget
/T <FEFF0078>
/V <FEFF>
>>
endobj
4 0 obj
<<
/Type /Annot
/DA (/rmtf 11.9552 Tf 1.1955 Ts 0 0 0 rg 0 0 0 RG)
/F 4
/Parent 2 0 R
/Q 0
/Subtype /Widget
/Rect [ 14.033054 14.033054 70.40415 25.08072 ]
>>
endobj
One of the tools that has issues with two objects for the signature
field is the latest version (1.18) from mupdf-gl.
mupdf-gl adds the signature value to the child (object 4) and not to its
parent (object 2).
I’m afraid this is also the same issue that AutoFirma (a e-signing tool
developed by the Spanish government
[https://firmaelectronica.gob.es/Home/Descargas.html]) has with these
signature fields.
When both objects are merged in one (as Acrobat Reader does when saving
a copy), both tools generate documents contaning signatures totally
unproblematic to be read validated by Acrobat.
I suggested merging both objects back in 2017. You told me that
simplifyng this would introduce too much complexity in ConTeXt only to
save some bytes.
Back then, I thought it was an minor improvement. Now I realized that
this two objects for signature fiels are only valid for Acrobat.
I wonder whether this improvement might be also easier to make in LMTX.
Would it be possible that signature fields may have only one object, so
that mupdf-gl and other tools have no problem signing fields PDF
documents generated by ConTeXt?
Many thanks for your help,
Pablo
--
http://www.ousia.tk
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