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How to Sign a Document with a Digital Signature (and what that means)

by Kristina Wagner

Smallpdf now supports Digital Signature for all Sign Requests, and for Pros signing their own documents. Try it out!

How to Request Verifiable Signatures

  1. Go to our eSign tool

  2. Choose "Request a Signature"

  3. Upload your PDF

  4. Add people who should sign the document and click "Next"

  5. Click "Finish & Send"

Smallpdf will then send your recipients a signature request. After the last person has signed the document, Smallpdf will seal the document with a digital signature. This feature is available for both Pro and Free users.

Sending a Signature Request

How to Sign a Document with a Digital Signature

Pro users with a verified email address have the protection of our Digital Signature on all signed documents, both self-signed and sent for signature. Here's how:

  1. Go to our eSign tool

  2. Upload the document you wish to sign

  3. Place a signature, and optionally add text to your document

  4. Click 'Apply'

Signing a Document

What is a Digital Signature?

When a document has a digital signature, anyone can verify that the document has not been tampered with since it was signed. If someone does tamper with or change the document after the digital signature was applied, it will be invalidated.

How do Smallpdf Digital Signatures work?

When you sign a document using our tool, we provide an Advanced Electronic Signature that also includes an LTV- (Long Term Validation-) enabled timestamp. Specifically, we use a certificate issued to us, Smallpdf GmbH, by a Swiss Trust Service Provider, SwissSign, to put a Digital Signature on your document.

A Digital Signature is a cryptographic process where a large number is calculated based on the contents of the document and the attached certificate. The certificate contains the name of the signer (in our case, Smallpdf GmbH). The number that is calculated for the document can be verified with software such as Adobe Reader DC.

Again, the Digital Signature can only be matched and verified if the content of the document is unchanged since the Digital Signature was applied AND the certificate is valid.

Can I verify the time when the document was signed?

Yes. In addition to our Digital Signature we add a timestamp that is also signed and thus cannot be faked. The timestamp records the exact time when the Digital Signature is placed on the document. For Smallpdf users, this is when Smallpdf processes the document.

Kristina Wagner
Research and Design

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