DIGITAL FILE MARKED BY A SERIES OF MARKS THE CONCATENATION OF WHICH FORMS A MESSAGE AND METHOD FOR EXTRACTING A MARK FROM SUCH A DIGITAL FILE

摘要

The marked digital file (10) comprises a plurality of portions, some of which (12) are marked with a mark (14) of a string of marks so as to form a string of marked portions (12). Concatenating the marks (14) of the string forms a message. Each mark (14) contains an identifier (I, 10 to 15, JO to J2) of the mark (14) defined by a numerical value, this value varying from one m.ark (14) to another as a function of the order of the mark (14) in the marked string. The string of marked portions (12) includes sub-strings, each of at least two markea portions (12) such that all of the portions (12), of a given sub-string are marked by the same mark (14).