Browse Prior Art Database

Document Source Security

IP.com Disclosure Number: IPCOM000045310D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Bell, CL: AUTHOR [+2]

Abstract

This cryptographic method maintains the readability of clear text while making it difficult to remove information identifying the source of a document. Substantially similar, but minutely different, type families provide the means for conveying the pertinent information.

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Document Source Security

This cryptographic method maintains the readability of clear text while making it difficult to remove information identifying the source of a document. Substantially similar, but minutely different, type families provide the means for conveying the pertinent information.

A conventional method to reduce the likelihood that unauthorized copies will be made of a document, especially a sensitive one, is to print the source identification on each page. However, if a copy is made, the source is easily effaced without reducing the readability of the text. The following is a method for identifying the source which can be used either overtly or covertly.

This method is based on the use of non-impact printers that have the ability to program different type families into the printer.

These printers can rapidly produce a personalized copy of a document that has been stored in the database. They also have the ability to program different type families into the printer. Two type families are designed to be very similar to each other, one of which, however, has a slight difference in each character from the corresponding character of the other that should be evident to a careful observer.

For example, such differences as serifs are ordinarily not noticed by a reader. A trained observer, consulting a copy of the two typefaces, if necessary, will easily determine from which of the two typefaces a printed character has come. These alternations between the two typefaces are used to encode the source of the document into the text.

A specific implementation is described as an example. Each document is assigned a specific serial number consisting of n (where n is a number typically from two to ten) de...