Net Q & A

Question of the Month: May 2002

What Is the Difference between a "digitized signature" and a "digital signature"?

Answer

A "digitized signature" is basically a picture of a handwritten signature that has been converted into computer format. To create a digital signature, take a handwritten signature (sometimes referred to as a "wet" signature), and run it through a computer scanner.

"Digital signatures" are completely different. They use mathematical formulas that combine a "hash" (unique number associated with an electronic document) with a pair of numbers associated with a particular person (the public and private keys, with the latter often being part of a "digital certificate").  Computers use these formulas in such a way that can establish, with a fairly high degree of certainty, that a digitally signed message:

For the sake of brevity, this explanation of digital signatures has been simplified, with some resulting loss of precision. More detailed explanations are available, including a good article at Findlaw and the chapter on e-mail security in the author's book The Complete Internet Handbook for Lawyers.

Jerry Lawson