Electronic vs Digital Signature: How Each Works and When You Need Which

"Please sign electronically." "A qualified digital signature is required." "Sign with your digital ID." These phrases show up in transactions every day, and many people use them interchangeably. But the difference is big: the first may mean drawing your signature with a finger; the second means a cryptographic signature that proves your identity and reveals any change made to the document after signing.

Knowing the difference protects you from two mistakes: sending a simple signature to an organisation that requires a digital one (and having your submission rejected), or assuming that a signature image protects a document from tampering. This guide explains both simply, without unnecessary jargon.

Electronic signatures: the broad concept

An electronic signature is any electronic data a person uses to indicate agreement with a document or transaction. Examples:

• Drawing your signature with a mouse or finger and placing it on a PDF.
• Pasting a scanned image of your handwritten signature into a document.
• Typing your name at the end of an email or form.
• Ticking an "I agree to the terms" box.
• Entering a one-time code texted to you to confirm a transaction.

Strength: easy, fast and widely accepted for everyday dealings. Many legal systems state that a signature can't be denied effect merely because it's electronic.

Weakness: a simple signature on its own doesn't prove who signed — anyone can copy a signature image — and doesn't stop the document being changed afterwards. Its evidential weight comes from surrounding evidence: which email it came from, the correspondence trail, the timing.

Digital signatures: secured by cryptography

A digital signature is a cryptographic technique built on public key infrastructure (PKI). In simple terms:

1. A key pair

Each signer has two mathematically linked keys: - Private key: secret, held only by the signer — often on a smart card, secure token or protected app. - Public key: shared openly and used for verification.

What's signed with the private key can be verified only with the matching public key, and can't be forged without the private key.

2. The hash (fingerprint)

When signing, software computes a unique digital "fingerprint" of the document's content — a short string that changes completely if a single character changes.

3. Signing

The fingerprint is encrypted with the private key and embedded in the PDF along with the signer's certificate.

4. Verification

When someone opens the document, their reader recomputes the fingerprint, decrypts the signature with the public key and compares. If they match, the document hasn't changed since signing. If not, a warning appears: "The document has been altered since it was signed."

5. The certificate: who vouches for the identity?

A public key alone doesn't say who owns it. That's the job of a digital certificate: an electronic document issued by a trusted Certificate Authority (CA) after verifying your identity, binding your name to your public key. If the reader trusts that CA, it trusts the signer's identity.

Side by side

What about "advanced" and "qualified"?

Some legal frameworks — most famously the EU's eIDAS Regulation (EU) No 910/2014 — define three levels:

1. Simple: any electronic signature.
2. Advanced: uniquely linked to and capable of identifying the signer, under the signer's sole control, and able to detect later changes. Usually implemented with a digital signature.
3. Qualified: an advanced signature created with a qualified signature creation device and based on a qualified certificate from an accredited trust service provider. In the EU it has the same legal effect as a handwritten signature.

In the US, the ESIGN Act and UETA give legal effect to electronic signatures generally, without mandating a specific technology, while particular agencies and industries may require stronger methods. Many other countries — the UK, Gulf states, Egypt and others — have their own electronic transactions laws distinguishing ordinary from certified signatures. Details vary by jurisdiction.

How to verify a digital signature in a PDF

1. Open the file in a reader that supports digital signatures, such as the free Adobe Acrobat Reader.
2. Look for a banner at the top or a Signatures panel on the side.
3. You'll see one of: - ✅ Valid: "Signed and all signatures are valid." Unchanged, trusted certificate. - ⚠️ Validity unknown: cryptographically intact, but the reader doesn't know the CA. You may need to trust the CA's certificate manually if you're sure about it. - ❌ Invalid: the document was changed after signing, or the certificate is expired or revoked.
4. Click the signature for details: signer name, issuing CA and signing time.

Important: browsers and many mobile apps display the PDF without checking digital signatures. To verify, use software that supports it.

A simple walkthrough

Sarah digitally signs a contract and sends it to Ahmed:

1. On Sarah's side: the software computes the contract's fingerprint — say a3f9….
2. It encrypts the fingerprint with Sarah's private key (on her smart card or secure app), producing the signature.
3. It embeds the signature and Sarah's certificate in the PDF.
4. On Ahmed's side: his reader recomputes the contract's fingerprint.
5. It decrypts the signature with Sarah's public key (from her certificate) to recover the original fingerprint.
6. It compares the two: they match, so the contract hasn't changed.
7. It checks the certificate: issued by a trusted CA, not expired, not revoked. So the signer really is Sarah.

If anyone changed a single digit after Sarah signed, Ahmed's fingerprint would differ and a warning would appear immediately.

Common mistakes

Believing a signature image protects the document. Putting your signature image on a PDF doesn't stop someone editing the text later while your signature stays. Nothing in the file would reveal it.

Editing a digitally signed file. Compressing, merging, adding a page — even re-saving with another tool — can invalidate a digital signature. Make all changes before signing.

Confusing seals with signatures. Under some frameworks an electronic seal is a digital signature on behalf of an organisation, proving the document's origin. Pasting an image of a company stamp is just a simple signature.

Ignoring certificate expiry. Certificates expire. Good systems add a trusted timestamp proving the signature was made while the certificate was valid, so verification still works later.

The right order: preparing a document for digital signing

Since any change invalidates a digital signature:

1. Write and finalise the document.
2. Save as PDF from the app.
3. Merge attachments if any, with Merge PDF.
4. Number pages with Add page numbers.
5. Compress if needed with Compress PDF.
6. Add any required watermark.
7. Sign digitally — last.
8. Change nothing afterwards. If you must, go back to the pre-signing version and redo the steps.

Multiple signatures

For multi-party contracts, several digital signatures can be added to the same file. Modern software saves each as a new "revision", so the first signature stays valid for the version its signer signed, and the second covers the document after the first. Signing must happen in sequence, in software that supports it, with no edits in between beyond what the document allows (like designated fields).

When is a simple signature enough?

Usually enough for: - Internal approvals at work. - Quotes and simple purchase orders. - Leases and service agreements between known parties, with correspondence kept — subject to local rules. - School forms and activity permissions. - Delivery and receipt acknowledgements.

You may need a certified digital signature for: - E-government transactions that specify it. - Formal banking and financial transactions. - Legal and court documents. - High-value contracts or ones likely to be disputed. - Public tenders in many countries.

How to get a digital signature

It depends on your country and purpose:

• Government digital ID: many countries provide an app or smart ID card enabling digital signatures for government services.
• Licensed commercial CAs: issue signing certificates to individuals and companies, usually for an annual fee, sometimes on a secure USB token.
• E-signature platforms: many offer advanced signatures with audit trails, and some offer qualified signatures through accredited partners.

Always start by asking the organisation requesting the signature: which type do they accept, and through which platform?

Simple signing with WPPR

Sign PDF lets you draw your signature and place it on the page you choose — inside your browser, without uploading the file. That's a simple electronic signature, suitable for everyday use. To strengthen it as evidence:

• Send the signed file from the email address the other party knows.
• Keep the correspondence and an exact copy of what you sent.
• Add your name and date with Header & footer.

Practical steps are in How to sign a PDF electronically without printing.

Quick glossary

FAQ

Are electronic signatures legal?

In many countries, yes — they can't be rejected merely for being electronic. But evidential weight varies by type, and some transactions require specific types or formal procedures.

Can I create my own digital signature?

Technically you can make a "self-signed" certificate, but readers won't trust it automatically, so it proves nothing about your identity to anyone. Meaningful digital signatures rely on a certificate from a trusted authority.

Why did my digital signature become "invalid" after compressing the file?

Compression rewrote the file, changing its fingerprint. Compress before signing, not after.

Is a scanned signature image a digital signature?

No. It's a simple electronic signature — an image on the page.

How do I know if a PDF is digitally signed?

Open it in Adobe Acrobat Reader or similar and look for the Signatures panel or the blue banner at the top.

Does WPPR create digital signatures?

No. It creates simple electronic signatures — your signature image on the page. For certified digital signatures you need a certificate from a trusted provider or an official platform.

Bottom line

"Electronic signature" is the broad umbrella for any electronic consent, the simplest form being your signature image on a page. A digital signature is a specific type that uses cryptography and certificates to prove who signed and reveal later changes. Choose based on what the transaction requires — and always ask the receiving party.

For everyday simple signing, use Sign PDF — free, and your file is never uploaded.

Sources

• eIDAS Regulation (EU) No 910/2014 (EUR-Lex)
• Digital signature (Wikipedia)
• Public key infrastructure (Wikipedia)
• ESIGN Act (Wikipedia)
• PAdES (Wikipedia)