The invention provides apparatus and methods for embedding and recovering
watermarking information based on host-matching codes. A code selector
provides codes to be embedded in the host signal. The code selector
associates distinct input data strings to be embedded into the host
signal with distinct code sets. Codes from the associated code sets are
selected to represent the input data strings based on an analysis of the
host signal (i.e. "host-matching"). The code selector may associate the
distinct input data strings with distinct code sets based on a predefined
mapping. An embedder embeds the codes into the host signal to provide a
watermarked signal. An extractor at a decoder extracts the embedded codes
from the watermarked signal. A code interpreter interprets the codes to
recover the data represented thereby. The interpreter may perform a
many-to-one mapping of an extracted code to the associated data string.