CODEWITHSUNDEEP
cryptographypdf-generationdigital-signatureencryption-asymmetric
Delayer
Delayer

Reputation: 439

May a PDF signed document signature reapplied?

I'm thinking about the case and pdf is dynamically generated according to a template and some data.

Until I keep the template the same and the data the same, may I reapply the same signature to the document or it will be invalidated?

You can read also as: is the public signature related only to content or depends on create time of the document,etc..?

Upvotes: 0

Views: 41

Answers (1)

mkl
mkl

Reputation: 95898

Until I keep the template the same and the data the same, may I reapply the same signature to the document or it will be invalidated?

If you re-generate the PDF byte-wise identically and in particular also identically prepare it for signing, the signed bytes are identical, so the identical signature can be used.

You can read also as: is the public signature related only to content or depends on create time of the document,etc..?

You said you want to keep the data the same. If the claimed creation time of the document is stored in the document (e.g. in the metadata), then that claimed creation time obviously must be part of the data you keep and re-use.

You can get a different best signing time, though, by using a digital time stamp for the signing time and nothing else because such a time stamp is applied as unsigned attribute.

Unfortunately you don't mention your PDF generation tool chain, so we can not check whether your tools allow such a faithful regeneration of PDFs.

Upvotes: 1

Related Questions