Locking a signed PDF using iTextSharp after Long Term Validation(LTV) has been added using LtvTimestamp -


is possible stop annotations , / or signatures being added after pdf has had ltv added using ltvtimestamp?

i've tried adding pdfsignatureappearance.certified_no_changes_allowed on initial signing adding ltv invalidates signature.

any appreciated.

in general

first of all, no, not possible stop annotations , / or signatures being added after pdf has had ltv added in general because 1 can program utility adding annotations or signature fields ignoring permissions.

so let's assume talking tools respecting permissions. in case question according specification permissions interpreted.

permissions in iso 32000-1

what changes or not allowed in iso 32000-1, has been described in this answer.

iso 32000-1 not know pades-4 ltv information or document time stamps. sees latter normal signatures using non-interoperable format , has no interpretation former.

thus, if initial signature certification signature "with form fill-in , digital signatures allowed" , there 1 empty signature field, may add document time stamp in empty field , no later signatures or annotations allowed.

unfortunately, though, adding validation related information (which 1 major reason ltv'ing after all) strictly speaking not allowed in certified document.

thus, tool interpreting permissions strictly according iso 32000-1 can persuaded not allow signature or annotation additions after document time stamp. such tool not target tool neither allows ltv vri nor able handle document time stamps let alone interpret whole "signed document ltv".

permissions in iso 32000-1 modified per pades part 4

pades part 4 changes situation specifying document time stamps , ltv vri, , ruling

docmdp restrictions (see iso 32000-1 [1] clause 12.8.2.2) shall not apply incremental updates pdf document containing dss dictionary , associated vri, certs, crls , ocsps. [...]

when evaluating docmdp restrictions (see iso 32000-1 [1], clause 12.8.2.2) presence of document timestamp dictionary item shall ignored.

(etsi ts 102 778-4 v1.1.2 "annex (normative): iso 32000-1 ltv extensions")

thus, if document is

  • either "certified no changes allowed" ltv validation related information , document time stamp added
  • or "certified form fill-in , digital signatures allowed" ltv validation related information , document time stamp added without remaining empty signature fields (probably enforced field locking)

is processed tool interpreting permissions according iso 32000-1 modified per pades part 4, tool will:

  • accept vri addition , handle them , document time stamp, and
  • not accept or create further signatures or annotations.

but accept further vri , document time stamp additions!

permissions in iso 32000-2 (draft)

the latest draft have available here integrates pades part 4 additions. thus, situation same in case of iso 32000-1 modified per pades part 4.

the new option change mdp permissions part of field locking may used have more lax situation before adding document time stamp.

adobe acrobat reader dc v 2015.007.20033

how software interprets permissions, has yet analyzed...


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