Tcpdf multiple signatures

Question

I am generating PDF files with tcpdf. So far, everything is ok.

I understand that it can only have one digital signature and it has to be created at creation time.

However I have some PDFs that have to be signed from multiple people and, not simultaneously. My app can generate different PCKS#7 signatures when each member decides to sign the text.

Is there a method by which I can add those multiple signatures by some raw insertion function? I do not need tcpdf to generate the signature, just put it to the file.

Best regards.

Yes, I have to sign again a signed pdf. PDF does not store multiple signatures at once, as I thought. Each signature signs the entire document, which may be signed. So signing is progressive. — Michael Chourdakis, Apr 23 '18 at 19:17
Incremental updates? Would you like to share how you did it? — paf.goncalves, Apr 23 '18 at 22:31
You simply use tcpdf to sign and then, you use it again on the same PDF. — Michael Chourdakis, Apr 24 '18 at 03:06
Do you use FPDI to open the first PDF and then signg again? Because i believe regular TCPDF can't open a PDF file. — paf.goncalves, Apr 24 '18 at 11:15
I just reviewed my code - I use pdfsign.js because signing takes place at the client side. — Michael Chourdakis, Apr 24 '18 at 14:59
please could you share with us the solution? thanks in advance. — Joel Meza Baca, Jul 18 '20 at 18:09

K4M · Answer 1 · 2020-08-08T04:02:11.933

UPDATE

setSignature() seems to have parameter for approvals and the documentation suggests that's for incremental update. The value can be 'A' for approval signatures.

@param $approval (string) Enable approval signature eg. for PDF incremental update

See my answer on this question for more details: PDF Multiple Digital sign

ORIGINAL VERSION

The library you use should support incremental update, which allows appending new section without modifying the original document that's been signed previously.

TCPDF does not support incremental update.

https://sourceforge.net/p/tcpdf/discussion/435311/thread/8cf24d19/

If you are going to do the signature verification through your app,and show that the document signature is valid, then you can do that saving the signature binary data into a hidden object but the signing and validation will not work inside Acrobat reader, just in your app.

In summary, look for a PDF generator that supports incremental update and thus multiple- signatures.

score 0 · Answer 2 · answered Nov 27 '19 at 10:04

0

I was looking for similar solution with tcpdf, it's working fine with one signature. When I try to sign again the document, the old signature is gone and the new signature is added. However the new document keep the old signature image only. So still looking for a way to add more digital signature in one pdf with different image as signature appearance.

answered Nov 27 '19 at 10:04

Hatem

200
1
10

are you can sign the document with more one signature ? – MAHA OUEGHLANI Feb 14 '23 at 14:57

Tcpdf multiple signatures

2 Answers2

Linked