Electronic signature vs digital signature
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Definition
An electronic signature is the legal act of signing electronically (a click, a typed name, a drawn signature), while a digital signature is a cryptographic technique that proves a document's integrity; the second often protects the first, but they are not synonyms.
These two terms get swapped constantly, including by people selling signature software, and the confusion matters because they answer different questions. 'Electronic signature' answers a legal question: did this person agree to this document? 'Digital signature' answers a mathematical one: has this file changed since it was signed, and who sealed it?
Electronic signature: the legal layer
Under the ESIGN Act, UETA, and eIDAS, an electronic signature is any electronic sound, symbol, or process attached to a record with intent to sign. The validity test is evidentiary, covering intent, consent, attribution, and record integrity. No cryptography is required by the definition; a typed name can be a fully enforceable electronic signature if the evidence holds up.
Digital signature: the cryptographic layer
A digital signature is public-key cryptography applied to a document: the contents are hashed, the hash is encrypted with a private key, and anyone with the matching certificate can verify both who sealed the file and that not one byte has changed since. It's the technology behind PAdES PDF sealing, qualified signatures in the EU, and the padlock your PDF reader shows.
How they work together
Good e-signature platforms use both layers: the electronic signature captures the human agreement with its consent and attribution evidence, and a digital signature then seals the finished record so it can't be altered undetectably. That's Sign Sail's model, with signer evidence (IP, timestamp, user-agent, SHA-256 hash, frozen form schema) inside the PDF and a PAdES cryptographic seal on the file itself.
↗ · Common questions
Which one is legally binding, electronic or digital?
The electronic signature is the legally operative act, since it's what expresses agreement. A digital signature on its own binds nobody; it's an integrity seal. Courts enforce the agreement evidenced by the electronic signature, and the digital signature strengthens that evidence by proving the record wasn't altered.
Do I need a digital certificate to sign a contract online?
Usually not. Standard business documents are signed with simple electronic signatures backed by an audit trail. Certificates enter the picture for EU Qualified Electronic Signatures and certain regulated documents. The platform's own certificate, used to seal the PDF, doesn't require anything from the signer.
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↗ · More terms
See it in a real signature.
Every Sign Sail plan, the free one included, captures this evidence on every signature.