88 research outputs found
Wide spread spectrum watermarking with side information and interference cancellation
Nowadays, a popular method used for additive watermarking is wide spread
spectrum. It consists in adding a spread signal into the host document. This
signal is obtained by the sum of a set of carrier vectors, which are modulated
by the bits to be embedded. To extract these embedded bits, weighted
correlations between the watermarked document and the carriers are computed.
Unfortunately, even without any attack, the obtained set of bits can be
corrupted due to the interference with the host signal (host interference) and
also due to the interference with the others carriers (inter-symbols
interference (ISI) due to the non-orthogonality of the carriers). Some recent
watermarking algorithms deal with host interference using side informed
methods, but inter-symbols interference problem is still open. In this paper,
we deal with interference cancellation methods, and we propose to consider ISI
as side information and to integrate it into the host signal. This leads to a
great improvement of extraction performance in term of signal-to-noise ratio
and/or watermark robustness.Comment: 12 pages, 8 figure
Encryption of Covert Information into Multiple Statistical Distributions
A novel strategy to encrypt covert information (code) via unitary projections
into the null spaces of ill-conditioned eigenstructures of multiple host
statistical distributions, inferred from incomplete constraints, is presented.
The host pdf's are inferred using the maximum entropy principle. The projection
of the covert information is dependent upon the pdf's of the host statistical
distributions. The security of the encryption/decryption strategy is based on
the extreme instability of the encoding process. A self-consistent procedure to
derive keys for both symmetric and asymmetric cryptography is presented. The
advantages of using a multiple pdf model to achieve encryption of covert
information are briefly highlighted. Numerical simulations exemplify the
efficacy of the model.Comment: 18 pages, 4 figures. Three sentences expanded to emphasize detail.
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