A system and method for unique authentication of each replication of a plurality
of soft-copy documents, forming a group. One soft-copy document, out of the group,
becomes a carrier for an authentication code aimed at protecting the group. The
authentication code is computed from the concatenation of the plurality of soft-copy
documents and a key. A random number is also generated for each replication of
the group of files. The random number is combined with the authentication code
to mark the soft-copy document which has been selected to become the carrier. Thus,
the invention introduces randomization in the insertion of the authentication code
so that for each replication of an identical group of data files, unique authentication
data can be associated, merged and hidden in the transmitted information.