A digital signature is an identifier that can be used to authenticate the sender of an electronic message (e-mail) or the signer of an electronic document. This technology can also be used to ensure the integrity of the message or document (that no alterations have been made since it was signed) as well as to date/time-stamp the document at signing. Finally, the signatory cannot easily repudiate or refuse to acknowledge his digital signature, nor can the document be easily forged.

Due to these criteria, a digital signature can be trusted and used like a written signature. On October 1, 2000, the Electronic Signatures in Global and National Commerce Act (known as the E-Signature Act) became effective in the United States. This act basically states that a signature cannot be denied simply because it is electronic, and an electronic signature must be considered as legally valid...