A system for determining the amount of processing that has been applied to watermarked
signal. A steganographic signal is provided that includes an original signal and
an embedded fragile watermark. The fragile watermark is characterized by a low
energy and a high redundancy in comparison to a robust watermark. The steganographic
signal is communicated over a distribution channel to a decoder. At the decoder,
a measure of a presence of the fragile watermark in the acquired steganographic
signal is provided, along with an estimate of the fragility profile of the fragile
watermark for this particular original signal. Based on these factors, a estimate
is made of the amount of processing that the steganographic signal has undergone.
This processing can include, for example, A/D and D/A conversions, resampling,
band-limiting, perceptual compression/decompression, etc. Optionally, the fragility
profile is derived prior to the distribution of the content and communicated by
the steganographic signal for recovery by the decoder. Furthermore, a robust watermark
may be provided in the steganographic signal that, e.g., designates the presence
of the fragile watermark to a decoder.