What is PAdES, and how is it different from an electronic signature?
PAdES (PDF Advanced Electronic Signatures, ETSI EN 319 142) is the standard for digital signatures embedded in a PDF: a cryptographic seal that identifies the signer and reveals later changes.
People use electronic signature, digital signature and PAdES as if they were the same thing. They are three layers: an electronic signature is any mark of intent, a digital signature is the cryptographic technique that proves who signed and that nothing changed, and PAdES is the way that technique is stored inside a PDF so every reader and verifier understands it. Sealique seals every signed PDF with PAdES signatures.
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Key facts
- PAdES stands for PDF Advanced Electronic Signatures and is defined by ETSI EN 319 142, the European standard that builds on ISO 32000 (PDF).
- A digital signature is a hash of the document encrypted with the signer's private key; anyone with the matching certificate can confirm the signer and detect changes.
- An electronic signature is the legal concept (any electronic mark of intent); a digital signature is one technology for it; PAdES is the PDF profile of that technology.
- A qualified electronic signature (QES) under EU eIDAS is a PAdES, XAdES or CAdES signature made with a qualified certificate on a qualified device; it is equivalent to a handwritten signature in the EU.
- Sealique applies a platform certification signature plus one PAdES signature per signer to every sealed PDF, and verifies them online with nothing to install.
What is an electronic signature?
An electronic signature is any data in electronic form attached to or logically associated with a document and used by the signer to sign: a typed name under an e-mail, a drawn signature on a phone screen, a click on an I agree button. Laws such as EU eIDAS Article 25 and the East African statutes give it legal effect, but on its own it proves little: anyone could have typed the name, and the document could have been edited afterwards.
What is a digital signature?
A digital signature is a cryptographic operation. The document is hashed (SHA-256 in Sealique), the hash is encrypted with the signer's private key, and the result is stored with the signer's certificate. A verifier decrypts it with the public key in the certificate and compares it with a fresh hash of the document: if the two match, the document is unchanged and the key holder signed it. A digital signature is therefore one way to make an electronic signature strong enough to be called advanced or secure.
What is PAdES?
PAdES is the profile that says how a digital signature lives inside a PDF: where the signature dictionary goes, how the byte range is computed, how several signatures are added as incremental updates without breaking earlier ones, and how long-term validation data is embedded. Because it is a standard (ETSI EN 319 142, building on ISO 32000), every compliant verifier reads the same structure. Sealique writes a certification signature by the platform first, then one approval signature per signer, each as a PAdES incremental update.
What is a qualified electronic signature (QES)?
In the European Union, eIDAS (Regulation (EU) No 910/2014) defines a qualified electronic signature as an advanced electronic signature created with a qualified signature creation device and based on a qualified certificate issued by a supervised trust service provider. Article 25(2) gives it the same legal effect as a handwritten signature. PAdES is the technical format; qualified is a level of assurance about who issued the certificate. Sealique signatures are PAdES signatures issued under the platform's own Root CA, not qualified signatures under eIDAS.
How does online verification of a PAdES signature work?
The public verification page reads every signature in the uploaded PDF, checks that each signed byte range still hashes to the signed value, validates the certificate chain against the Sealique Root CA, and compares the whole file's SHA-256 fingerprint with the copy stored when the document was sealed. It then shows each signer's name and time, whether the file is intact, and whether it is a flattened or modified copy. The same check runs when a QR code or verification ID is used, so nobody needs to install software.
What PAdES explained includes
- PAdES signature per signer, applied as an incremental update
- Platform certification signature on every sealed PDF
- SHA-256 fingerprint stored at sealing and compared on verification
- Online verification by QR code, verification ID or upload
- Certificate of completion with the audit trail
Questions people ask
Is PAdES the same as a digital signature?
PAdES is the PDF-specific format for digital signatures; every PAdES signature is a digital signature, but digital signatures also exist in other formats (XAdES, CAdES).
Is a PAdES signature legally valid?
Yes in most jurisdictions: it meets the advanced or secure signature tests of eIDAS and of the Rwandan, Kenyan, Ugandan and Tanzanian laws.
Whether it counts as qualified depends on who issued the certificate, not on the PAdES format.
Can I verify a PAdES signature without special software?
Yes. Upload the PDF, scan its QR code or type its verification ID on the Sealique verification page; the check runs online.
What happens to a PAdES signature if someone edits the PDF?
The signed hash no longer matches the document, so the verification page reports the file as modified after sealing.
The sealed copy kept on the server also lets the page show what the original looked like.
Does Sealique issue qualified electronic signatures?
No. Sealique issues PAdES signatures under its own Root CA; qualified signatures require a certificate from a supervised qualified trust service provider.
Sources
- Regulation (EU) No 910/2014 (eIDAS), Article 25
- eIDAS compliance overview (law4devs)
- UNCITRAL Model Law on Electronic Signatures (2001)
This page is a plain-language summary, not legal advice; check the current text of the law for your document type.