Electronic vs Digital Signatures in PDFs, Explained

The difference between electronic and digital signatures in a PDF is what they can prove. An electronic signature is any electronic data a person uses to sign, such as a drawn or typed name. A digital signature is a certificate-based, cryptographic kind of electronic signature that can show who signed and whether the file changed afterwards.

People often use the two terms as if they meant the same thing. For a supplier letter that rarely matters. For a signed protocol, a quality agreement or a document sent to a regulator, it can. This article explains the difference, the EU and US rules that pharma, biotech and medtech teams most often meet, and how to check a signature yourself. It is general information, not legal advice.

What counts as an electronic signature?

The EU eIDAS Regulation (Regulation (EU) No 910/2014) defines an electronic signature very broadly, in Article 3(10), as data in electronic form attached to or logically associated with other electronic data and used by the signatory to sign. A typed name, a signature drawn with a mouse and a scanned image of a handwritten signature all fall within that definition.

In a PDF, these are visual signatures: marks placed on the page. They show intent, but nothing in the file ties the mark to the content or to a verified person. Anyone can copy the image onto another document, and the page can be edited after the mark is added without leaving any technical trace.

What makes a digital signature different?

A digital signature uses a certificate and a private key. When you sign, the software calculates a fingerprint (a hash) of the document and signs that fingerprint with your private key. The result, together with your certificate, is stored inside the PDF. A reader can then recalculate the fingerprint and check it against the signature. If a single byte of the signed content has changed, the check fails.

The European standard for this in PDF files is PAdES, published by ETSI as EN 319 142. It defines baseline levels from PAdES-B-B to PAdES-B-LTA; the higher levels add elements such as timestamps and validation data so a signature can still be checked years later. ETSI describes a digital signature as data that allows a recipient to prove the source and integrity of the data.

The US rule uses similar language: 21 CFR 11.3 defines a digital signature as an electronic signature based on cryptographic methods, such that the identity of the signer and the integrity of the data can be verified.

What are the three eIDAS signature levels?

eIDAS describes three levels. The lowest is often called a simple electronic signature: anything that meets the Article 3(10) definition.

• Advanced electronic signature. Under Article 26 it must be uniquely linked to the signatory, capable of identifying them, created with data the signatory can use under their sole control, and linked to the signed data so that any later change is detectable.
• Qualified electronic signature. Under Article 3(12) it is an advanced electronic signature created by a qualified signature creation device and based on a qualified certificate for electronic signatures.

The level matters because of Article 25. An electronic signature cannot be denied legal effect or admissibility as evidence solely because it is electronic or is not qualified (Article 25(1)). But only a qualified electronic signature has the equivalent legal effect of a handwritten signature (Article 25(2)), and one based on a qualified certificate issued in one Member State is recognised as qualified in all others (Article 25(3)).

eIDAS was amended by Regulation (EU) 2024/1183, which established the European Digital Identity Framework. That amendment did not change Article 25. For regulatory work in the EU, the EMA's harmonised eCTD guidance states that, for EMA submissions, qualified and advanced electronic signatures are in general accepted.

What does 21 CFR Part 11 require?

In the United States, 21 CFR Part 11 applies to electronic records created or kept under FDA record requirements, and to electronic signatures on them. It is not a PDF format rule; it is a set of system and procedural controls. Among other things:

• Signed records must show the printed name of the signer, the date and time of signing, and the meaning of the signature, such as review or approval (§ 11.50).
• Signatures must be linked to their records so they cannot be excised, copied or transferred to falsify a record by ordinary means (§ 11.70).
• Each electronic signature must be unique to one person, and the organisation must verify the person's identity before assigning it (§ 11.100).

A PDF tool on its own does not make a signature Part 11 compliant; your validated system and procedures do. Our article on online PDF tools in pharma and GMP work covers the wider questions.

How do you check a signature in a PDF?

Open the file in a full PDF reader that validates signatures, such as Adobe Acrobat Reader, and open the signature details. A proper validation answers three questions:

1. Has the document changed since it was signed? This is the integrity check, and the most important one.
2. Who signed it? The name comes from the certificate, not from anything drawn on the page.
3. Is the certificate trusted? A self-signed certificate, or one from an issuer your reader does not trust, identifies the signer only as far as you trust whoever created it.

If the reader shows no signature at all, the document only has a visual signature, and there is nothing cryptographic to check.

Which Priya LifePDF tool does what?

• Sign PDF adds a visual signature: you draw, type or upload one in the PDF viewer and place it on the page. It does not add a certificate. Our guide on how to sign a PDF walks through it.
• Digital Sign PDF adds a certificate-based signature using your own PFX, P12 or PEM certificate file, with an optional visible signature box. It creates a standard PDF signature of the type adbe.pkcs7.detached, not a PAdES baseline signature, and it does not add a trusted timestamp. Whether a signature counts as advanced or qualified depends on your certificate and how you control it, not on this tool.
• Validate Signature lists the signatures in a PDF and shows the signer, issuer, certificate validity dates and algorithms, and can compare the chain against a trusted certificate you supply. It does not verify that the document is unchanged since signing. Always confirm integrity in a full PDF reader such as Adobe Acrobat Reader.

All three run in your browser, so your document and certificate are not uploaded to our servers. Priya LifePDF is a general-purpose tool, not a validated GxP system, and it does not create qualified electronic signatures.