E-signature vs digital signature — the real difference
People use "e-signature" and "digital signature" interchangeably. They aren't the same thing. Here's the technical distinction that actually matters in court.
The terms get swapped constantly. They aren't the same.
Electronic signature (e-signature) is the legal category — anything that shows intent to sign, from a typed name to cryptographic PAdES.
Digital signature is a specific cryptographic technology — the use of Public Key Infrastructure (PKI) to bind a signature to a document using asymmetric encryption. Every digital signature is an e-signature; not every e-signature is a digital signature.
How digital signatures work (the math)
1. The signer has a private key (never leaves their device/HSM) and a public key (distributed via X.509 certificate). 2. Signing software computes a SHA-256 hash of the document content — a 256-bit fingerprint that changes if any byte changes. 3. The hash is encrypted with the signer's private key. This encrypted hash is the digital signature. 4. Anyone can verify: decrypt the signature with the signer's public key, recompute the hash from the document, compare. If they match, the signature is valid AND the document hasn't been tampered with.
This is the standard behind SignBolt's PAdES signatures, TLS certificates, Bitcoin, and SSH keys.
What a plain e-signature can't do
A typed name or click-to-accept:
- Can't prove the document hasn't been modified after signing
- Can't cryptographically bind the signer's identity
- Relies entirely on the platform's audit log for evidence
A digital signature:
- Detects any modification to the document (even one byte)
- Cryptographically binds the signer's identity via certificate
- Is self-verifying — any PDF reader with certificate validation can confirm authenticity without calling the signing platform
When each is appropriate
- Click-to-accept: ToS agreements, low-value consents
- Typed name + email verification: NDAs, casual contracts
- Digital signature (AES): most business contracts, employment agreements, vendor contracts
- Qualified digital signature (QES): EU regulated transactions, notarizations, some real estate
The SignBolt default
SignBolt produces digital signatures (AES level) by default — not just e-signatures. That means every signed document has cryptographic tamper-detection, not just a "signed by" log entry.
Pair with SnapPDF for document prep and you have the full lifecycle. Related: What is PAdES?
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