Extract/Read digital signatures from PDF

Hello,

we’re currently facing problems reading/extracting digital signatures from a PDF.

Solutions we looked into:

  • ReadPDFText: Using the Read PDF Activity it’s sometime possible to extract signatures with string manipulation but since we don’t know where the people will sign and which size the signature will be, we do not have consitent results.
  • Adobe Sign API: Apart from the fact that it costs something, you cannot extract signatures which weren’t signed via the Adobe Sign platform. Correct me if I’m wrong though.
  • UI-Automation: It’s obviously the worst way to automate this, but so far it seems to be the most consistent. We’d basically be automating the UI of Adobe Acrobat Reader to show all the signatures and use Read Text to extract the names. This kind of works.

Our next problem is that people sign the PDF in different locations and we only need the signatures from certain locations.

This is not possible with UI-Automation.
The next idea would be to extract all signatures via UI-Automation and used ReadPDFText to try to find where each signature resides on the pdf.

I really hope someone here has a better approach.
Curious to read what you think!

Cheers,
T0Bi

2 Likes

Hello T0Bi,

Kindly refer this https://opensource.adobe.com/dc-acrobat-sdk-docs/acrobatsdk/pdfs/acrobatsdk_jsdevguide.pdf

Read Page: 154-155
Heading: Getting signature information from another user.

You might need to do a small workaround to get the Javascript running in a PDF application.

Cheers,
Digvijay

1 Like

I resolved to doing something similar.

I used the Spire.PDF nuget package to write myself some C# code which I turned into an activity.

I’ll release the activity on the marketplace once it’s somehow production ready, but if anyone’s interested, I basically used this code:

https://www.e-iceblue.com/Tutorials/Spire.PDF/Spire.PDF-Program-Guide/Get-and-Verify-Digital-Signature-in-PDF-with-C-Code.html

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