Software Copy Protection by Controlled Damage
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
Unauthorized copying of programs on a magnetic disk is prevented by physically damaging some portion of the disk so that such area will not record any data. Attempts to read such damaged area always produce the same result regardless of any attempts to write in the damaged area. A routine is included within the program software to write and read at the damaged area. If the read pattern matches the written pattern, then the disk cannot be the original, but rather must be a copy of the original. The following are some examples of techniques used to create damaged areas on the disk: (1) mechanical scraping; (2) laser ablation of the disk surface; (3) grinding; (4) embossing; (5) punching; (6) chemical attack; (7) masking, i.e.