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Sign PDF files correctly
Note the order – signature comes last
Furthermore, the use of simple and intuitive solutions such as Adobe Sign and Docu Sign is increasing. These can be used to quickly replace an established signature process in the company with an end-to-end digital process. The technical quality of these digital signatures is quite low, but where there are no legal requirements, these solutions may suffice. The introduction is so simple that subsequent processes, such as archiving, are usually not considered.
Attention! Error! “Document was changed or damaged after signing”
Alternatively, the customer can set our PDF/A workflow so that a PDF file is not adapted to the PDF/A standard if it is signed. In this case, the signature will of course remain in tact, but the PDF file may not be suitable for long-term use.
Receive signature information
Delete signature
Not all signatures are visible. However, a visible signature is a popular addition to a digital signature. It has nothing to do with the actual cryptographic process. Unfortunately, it is not possible to remove this visualization when removing the digital signature. In terms of program technology, it is not possible to determine which visible object in the PDF was once applied to visualize the signature. However, it is perhaps also a good thing if at least this seemingly manual signature is retained.
Hackers can change a signed PDF without breaking the signature! Can we do the same?
So there’s no chance to help out here in a positive sense to get PDF/A customization and signature under one roof.
Pick up everything and combine in one container
The PDF/A file generated by us (after the signature has been removed) becomes an envelope file. And this envelope contains the original, non-standardized but signed PDF. An XML file with the determined signature information can also be placed in the envelope. This idea has been around for quite a long time, but is only now gaining acceptance among our customers.
As a technical overkill, the customer can also secure this container with a digital seal (*) from his own company; for a total increase in credibility.
(*) What is a seal? Cryptographically like a signature, only in practical use with a different meaning (as a counterpart to electronic signatures for natural persons), the eIDAS Regulation also introduced electronic seals which, unlike a signature, can also be used by organizations (legal entities). What is described in this article as a problem with signatures also applies to seals.
Summarized – Workflow for PDF/A with signature
In accordance with archiving regulations, many of our customers are currently converting from PDF to PDF/A. No problem with our PDF/creation process. However, when adapting digitally signed PDF files, a few special features must be observed in order to avoid error messages when reading the PDF.
Follow these steps:
- Read Signature Information – Extract the signature details from the document.
- Remove Signature – Delete the existing signature from the document.
- Adapt to PDF/A – Convert the document to PDF/A format using our PDF/A creation process.
- Generate PDF/A-3 with Embedded Original File and XML – Create a PDF/A-3 file, embedding the original document and including the original signature information in XML format.
- Seal the Container – Apply a digital seal to the entire document container.