CREATING AUTHENTICATABLE PRINTED ARTICLES AND SUBSEQUENTLY VERIFYING THEM BASED ON SCATTERED LIGHT CAUSED BY SURFACE STRUCTURE

A printer with integral scanner for obtaining a digital signature from a sheet of paper or other article as it is printed. The integral scanner has a coherent source which directs a light beam to illuminate the article and a detector arrangement to collect data points from light scattered from many different parts of the article to collect a large number of independent data points, typically 500 or more. The digital signature derived from the data points is stored in a database with an image of what was printed on the article. At a later time, the authenticity of an article purported to be the originally printed article can be verified by scanning the purported genuine article to obtain its digital signature. The database is then searched, to establish whether there is a match. If a match is found, the image stored in the database with the matched digital signature is displayed to the user to allow a further visual check that the article is genuine. The image is displayed together with other relevant bibliographic data relevant to the article.