A digital signature is much more than an electronic signature. Digital signatures become intrinsically linked to the content of the digital document using encryption. Anyone digitally signing a document needs a digital certificate; the certificate being unique to that individual. The certificate contains a public and a private key – known as a ‘key pair’. Digital signatures are like a lock on a document. If the document changes after the signature is applied, it will show up as an invalidated signature.Digital signatures are very secure. Hashes cannot be easily undone and encryption using a digital certificate is highly secure .A digital signature is hard to deny. This is also known as non-repudiation. A digital signature is associated with an individual’s private key of a digital certificate. This identifies them as being the signatory, as it is unique.