Asymmetric schemes belong to second generation of watermarking. Whereas their need and advantage are well understood, many doubts have been raised about their robustness. According to a method presented in [1], a very robust symmetric technique is derived into an asymmetric scheme. Tests show that it is as robust as the symmetric version. Yet, asymmetric schemes undergo malicious attacks that confuse the detection process. Tests reveal that the quality loss due to these malicious attacks is too important for the signal to be used after the attack.