Concepts
Document formats
PDF and XML packages own document mutation while sharing the same signing capability.
A document format package decides where bytes go. PDF owns visible rectangles, PAdES placeholders, byte ranges, and validation policy. XML owns canonicalization, transforms, references, and XML-DSig placement. Both consume Signatures; neither owns the signer backend.
Format responsibilities
- Parse or prepare the document.
- Derive the bytes that must be signed.
- Ask
Signaturesto sign those bytes. - Embed the artifact back into the document.