Comments on "Why Watermarking is Nonsense"

The security issues involved with digital watermarking are discussed. In this regard, the computational complexity of detecting a known watermark that has passed through an unknown channel is presented. In a watermark system, the cryptographic keys play an important rule in data security. A watermark detection test to define the probability of correct detection, where the keys are shared between the encoder and detector but unavailable to the attacker, is also discussed.