Methods and apparatus are provided for embedding information in a host signal
based on the positioning of watermarks within the host signal. An embedder provides
(i.e. embeds) a plurality of watermarks in the host signal. A processor associated
with the embedder is provided for determining a relative position for embedding
of at least two of the plurality of watermarks within the host signal such that
the relative position of the watermarks represents the embedded information. The
present invention also includes corresponding methods and apparatus for extracting
the embedded information from the host signal based on the detected relative positions
of the watermarks within the host signal, as well as computer readable medium containing
the host signal which carries the embedded information.