Electronic & Digital Signatures 

Signatures have been used as a proof of authorship since documents were first used. There have also been used as an indication that the signer agreed with the contents of the document at the time of signing. Signatures are used for a variety of reasons;

• a signature convinces the document's receptient that the signer deliberately signed the document,
• a signature is proof the signer, and no-one else, deliberately signed the document,
• a signature is part of the document and it can not be resused on a different document,
• after the document is signed it can not be altered,
• a signature and the document are physical items. The person signing the document can not claim at a later date that they did not sign it.

In reality written signatures can be forged, signatures can be moved from one piece of paper to another, and documents can be altered after signing them. However, it is difficult to do this without being detected and signatures therefore remain and effective means of authenticating documents.

With the advent of easy to use modern computers we have seen an explosion in the number of electronic documents generated. It would be useful to be able to authenticate electronic documents with an electronic signature.

Indeed many jurisdictions around the world now recognise electronic signatures as legally binding in appropriate circumstances.

An electronic signature is a, symbol, or process, attached to or logically associated with a record and executed or adopted by a person with the intent to sign the record.

An enforceable electronic signature can include agreements made via email, by entering a person identification number into a bank machine, or  'signing' a credit/debit slip with an electronic pen pad device at a sales counter.

With many methods of electronic signature, or imputed signature, its is relatively easy to forge or spoof assent. Fraud is a common issue in all signature situations, and neither type of signature (paper or electronic) provides fully effective anti-fraud protections.

Digital signatures attempt to overcome some the limitations of electronic signatures by using cryptographic means. Digital signatures offer cryptographic assurance of the sender's identity, and provide an integrity check on the text received

Commonly today digital signatures are implmented utilising public key infrastructures (PKI). PKI schemes attempt to unbreakably bind user information (name, address, phone number, etc.) to a public key, so that public keys can be used as a form of identification. Typically, a user signs the electronic document with a private key and the signed document and signature can be verified using the matching public key.

Digital signatures are usually issued to users by a certificate authority who will verify the users identitiy before issuning them with the digital signature.