Shrink PDF but keep e-signature certificate?

[ramiro_5353]

Hi team - apologies, but my google-fu is failing me - only getting spammy sites with no real value results.

I need to shrink PDFs (over 10k of them, in PDF/A format)  but keep the e-signature completely intact.   Using a CLI tool on Linux but it scrapes off the certificate during the removing PDF/A, shrinking, and re-PDF/A-ing.   

Can anyone advise a dummy like me?  Thanks!

[MikelKlink · Accepted solution]

Do you by "e-signature" mean anything involving digital signatures? Like either they are digital signatures themselves or they are covered by a digital signature (like Adobe Acrobat Sign usually does)?

In that case you are out of luck if you want to keep those signatures valid: digital signatures contain a hash of the bytes of the signed file. Any shrinking of the document changes that hash and so invalidates the signature.

Otherwise, i.e. if you mean something else by "e-signature", please explain.

[ramiro_5353]

Digital Signature with a certificate.  So yes, sounds about right about having the hash.  Makes sense, because you want that certificate only for that file and any changes invalidate the cert.  OK thanks, I really appreciate it here