The Confusion Between Digital and Electronic Signatures
The terms “digital signature” and “electronic signature” are often used interchangeably, but they refer to fundamentally different technologies with different legal implications. Understanding the distinction is important for anyone who signs or processes PDF documents in a business context.
What Is an Electronic Signature?
An electronic signature (e-signature) is any electronic indication of intent to agree to or approve the content of a document. This is a broad legal concept that includes:
- A typed name at the bottom of an email
- A scanned image of a handwritten signature placed on a PDF
- A drawn signature on a touchscreen
- Clicking an “I Agree” button on a website
- A stylized text representation of a name
Electronic signatures are legally valid in most jurisdictions for most purposes. The US ESIGN Act (2000) and the EU eIDAS Regulation (2014) both recognize electronic signatures as legally equivalent to handwritten signatures, with some exceptions (wills, certain real estate transactions, court orders).
The pdfs.to Sign PDF tool creates electronic signatures by embedding a drawn or uploaded signature image directly into the PDF at a specified position. This is the most common type of signature for routine business documents.
What Is a Digital Signature?
A digital signature is a specific type of electronic signature that uses cryptographic technology (Public Key Infrastructure, or PKI) to provide three guarantees:
- Authentication: The signature is linked to the signer's identity through a certificate issued by a trusted Certificate Authority (CA).
- Integrity: Any modification to the document after signing invalidates the signature, making tampering detectable.
- Non-repudiation: The signer cannot deny having signed the document, because the signature is mathematically linked to their private key.
Digital signatures are embedded in the PDF as cryptographic data, not as visible images. When you open a digitally signed PDF in a PDF reader, the reader verifies the certificate chain and displays a validation status (valid, invalid, or unknown).
Key Differences
| Feature | Electronic Signature | Digital Signature |
|---|---|---|
| Technology | Image, drawn mark, typed name | PKI cryptography (RSA, ECDSA) |
| Authentication | Varies (IP address, email, login) | Certificate from trusted CA |
| Tamper detection | No | Yes — any change invalidates the signature |
| Non-repudiation | Weak (depends on audit trail) | Strong (mathematically provable) |
| Legal validity | Broadly accepted (ESIGN, eIDAS) | Accepted everywhere; required for some regulated uses |
| Visual appearance | Visible signature image | May have visible representation + invisible cryptographic data |
| Ease of use | Simple — draw or upload | Requires certificate and signing software |
| Cost | Free or low-cost | Certificate costs vary ($0 to $500+/year) |
When to Use Each Type
Use Electronic Signatures When:
- Signing routine business documents (NDAs, proposals, approvals)
- Both parties trust each other and do not need cryptographic verification
- Speed and convenience are priorities
- The document does not fall under a regulatory requirement for digital signatures
- Internal company workflows (expense approvals, timesheets, PTO requests)
Use Digital Signatures When:
- Regulatory compliance requires it (e.g., FDA 21 CFR Part 11 for pharmaceutical documents)
- The document must be tamper-evident (contracts with significant financial value)
- Non-repudiation is critical (the signer must not be able to deny signing)
- Government filings or court submissions require certified signatures
- Cross-border transactions where trust between parties is limited
How to Add an Electronic Signature with pdfs.to
- Open the tool: Go to pdfs.to Sign PDF.
- Upload your PDF: Drag and drop the document to be signed.
- Draw your signature: Use the signature pad to draw your signature with a mouse or touchscreen, or upload a PNG image of your signature.
- Position the signature: Choose where the signature should appear — top or bottom of the page, aligned left, center, or right. Select small, medium, or large size.
- Click Sign: The signature image is embedded into the PDF as page content (not an annotation), making it permanent and visible in any PDF viewer.
- Download: Your signed PDF is ready to share.
Combining Both Types
In practice, many organizations use both types together: an electronic signature (visible image) for human recognition, and a digital signature (cryptographic certificate) for machine verification. The visible signature tells the reader who signed; the digital certificate proves it.
The pdfs.to Sign PDF tool handles the electronic (visual) signature. For cryptographic digital signatures, you will need a signing certificate from a Certificate Authority and a tool like Adobe Acrobat, Foxit PhantomPDF, or an enterprise signing platform.
Frequently Asked Questions
Is an electronic signature legally binding?
Yes, in most jurisdictions and for most document types. The US ESIGN Act, the EU eIDAS Regulation, and similar laws in over 60 countries recognize electronic signatures as legally equivalent to handwritten signatures. Exceptions exist for wills, certain real estate deeds, and court-specific filings.
Can someone forge an electronic signature?
Technically, yes — an image-based electronic signature can be copied. This is why important documents often pair electronic signatures with audit trails (IP address, timestamp, email verification) or upgrade to digital signatures with PKI. For routine documents, the convenience of electronic signatures outweighs the risk.
Do I need a paid service for digital signatures?
Free digital signing certificates are available from some CAs (e.g., Sectigo, Let's Encrypt for S/MIME). However, certificates from well-known CAs that are trusted by Adobe Reader out of the box typically cost $50–$500 per year depending on the validation level.