PAdES

Definition

PAdES (PDF Advanced Electronic Signatures) is the set of ISO standards that govern how a digital signature is carried by a PDF: the signature’s data sits inside the document, attached to a certificate, alongside a signing time and a statement of what changed after signing. A signature applied this way can later be examined to report the certificate, the signer, and whether the document was modified afterward. Applying one is a server-side operation; reading one back is verification.

Example

A counterparty receives a signed addendum and wants to confirm the signature is the signer’s and the file was not altered. The signature panel of the reader reports the certificate that was used, the signing time, and that the document has not changed since. That report is what a PAdES signature carries; a drawn image of a signature carries none of it.

In the PDFLean tools

• sign a PDF with a digital certificate — applies a PAdES signature with reason and location; runs on the encrypted cloud path
• verify a PDF signature — reads a signature back and reports certificate, signer, and integrity

Related reading

• Flattening — the separate question of whether field values display
• Form Field — signature placeholders as one field type among others
• Sign a Contract and Return It — the operational sequence a PAdES signature belongs to