Verify signed Documents

[rbonazzo-KZ]

Hi thank you for your fantastic job.
In Italy, in many cases, documents are signed via a PDF file with the .p7m extension added. So, for example, I have documentname.pdf.p7m. Can I use your tool? In my case, I never have the PEM file available.

[Lucas-C]

Hi @rbonazzo-KZ

Thank you for reaching out 🙂

Currently pdfly does not support .p7m files, but I added your feature request to there: #71

I looked for some information about .p7m file and I found this: https://cknotes.com/explaining-p7m-and-p7s-files/

For now, I think you could try to use the openssl to convert your .p7m file into a .pem file, and then use it with pdfly.
cf. https://knowledge.digicert.com/solution/how-to-convert-pkcs-7-to-pem-certificate-format-using-openssl

[rbonazzo-KZ]

Hi @Lucas-C
Thanks for your reply.
I managed to extract the PEM with this command:
openssl pkcs7 -inform DER -in document.pdf.p7m -print_certs -out cert.pem

The cert.pem is correct
by running
pdfly check-sign document.pdf.p7m --pem cert.pem
error:
Invalid value: Signature missing
where am I going wrong?

[Lucas-C]

That means that your PDF file does not contain a valid Signature.

If you can share it publicly, I'd be happy to have a look at it.

Else you can try to inspect its content, for example using qpdf: https://py-pdf.github.io/fpdf2/Development.html#qpdf

You could also try to get a .crt file from your .pem file: https://stackoverflow.com/a/14484363/636849
And then pass the .crt file to pdfly check-sign document.pdf.p7m --pem

[rbonazzo-KZ]

Hi I will try to replicate with an other document that I can share publicy