| 摘要 |
Disclosed are arrangements encode protection marks (302) into an unprotected document, where the protection marks are modulated according to a attributes of corresponding areas (902) of the unprotected document associated with the protection marks (302). Unauthorized amendment of the protected document can be detected by demodulating (1107) the modulated protection marks in the protected document, to derive the attribute of the unprotected document. This is compared to the corresponding attribute of the protected document, and this comparison indicates if unauthorized amendment has taken place.
|
