Signature Model
Method (Single / MultiShared / MultiChained) and Certify (DocMDP levels), field by field
Two enums shape what kind of signature sign_pdf produces: Method decides how the field(s) are
laid out across placements, and Certify decides whether the signature is a certifying (DocMDP)
signature or an ordinary approval.
Method
How the signature field(s) are laid out across the resolved placements.
Prop
Type
MultiChained cannot certify
certify is not compatible with Method::MultiChained — MultiChained signs its first revision by
a full rewrite, which Adobe rejects for a certifying (DocMDP) signature. Certify with
Method::Single or Method::MultiShared, then append further approval signatures via additional
sign_pdf calls, or use add_locked_signature to
lock the end of the chain.
Method is also incompatible with SignConfig::target_field when set to MultiChained — signing
into an existing named field requires Single or MultiShared.
Certify
A certifying (DocMDP) signature locks the document and declares what changes stay allowed
afterwards. Only the first signature in a document can certify; SignConfig::certify = None (the
default) makes an ordinary approval signature instead.
Prop
Type
pub fn level(self) -> i64Certify::level() returns the PDF DocMDP /P value written into the certifying signature's
/Reference transform params:
| Certify | /P level | Meaning |
|---|---|---|
Locked | 1 | No changes allowed. |
FormsAndSignatures | 2 | Forms + signing allowed. |
FormsSignaturesAndAnnotations | 3 | Forms + signing + annotations allowed. |