Abstract: Techniques for incorporating authentication information into digital representations of objects and using the authentication information to authenticate the objects. The authentication information may be made from information in one portion of the digital representation and incorporated into another portion of the digital representation that does not overlap the first portion. Where the digital representation is made into an analog form and that in turn is made into a digital representation and the second digital representation is verified, the two portions must further be non-overlapping in the analog form. The information from which the authentication information is made may exist at many levels: representations of physical effects produced by the object, representations of features of the object, codes that represent the object's contents, and representations of descriptions of the object. Also disclosed are a verification server and techniques for reducing errors by an OCR.