Though the two terms sound similar, digital signatures are different from electronic signatures.  While digital signature is a technical term, defining the result of a cryptographic process that can be used to authenticate a sequence of data, the term electronic signature — or e-signature — is a legal term that is defined legislatively.

This means that a digital signature — which can be expressed digitally in electronic form and associated with the representation of a record — can be a type of electronic signature. More generally though, an electronic signature can be as simple as the signer’s name being entered on a form on a webpage.

To be considered valid, electronic signature schemes have to encompass three things:

• a way to verify the identity of the entity signing it;
• a way to verify that the signing entity supposed to verify the document being signed; and
• a way to confirm that the electronic signature is certainly related with the signed document.

A digital signature can, on its own, fulfill these requirements to serve as an electronic signature:

• the public key of the digital signature is linked to the signing entity’s identification;
• the digital signature can solely be affixed by using the holder of the public key is related private key, which implies the entity intends to use it for the signature; and
• the digital signature will only authenticate if the signed data — record or representation of a document — is unchanged. If a record is altered after being signed, the digital signature will fail to authenticate.

While authenticated digital signatures provide cryptographic proof that a document was once signed via the stated entity and that the document has not been altered, not all electronic signatures can provide the equal guarantees.