Document copying deterrent method using line and word shift techniques

摘要: A method is provided that deters the illicit copying of electronically published documents. It includes publishing a plurality of copies of electronically created material to be distributed to a plurality of subscribers. Each copy of subscriber's document has a unique identification code embedded in the document. The arrangement of the code on the document is based on the line-shifting and word-shifting techniques. This is to minimize the effects from noise and distortions on future illicit copies to simplify detection and decoding of the unique code. A codebook is created to correlate each unique code with each subscriber.