The present invention generally relates to steganography and digital watermarking. An authentication method is provided in one embodiment. The method includes receiving an object including a host object and auxiliary data steganographically embedded within the host object; determining geometric characteristics of the host object relative to expected geometric characteristics of the host object; and detecting the auxiliary data from the host object. The method can further include re-aligning or correcting geometric characteristics of the object based on a result of the act of determining prior to the act of detecting. Other embodiments, method and apparatus and described as well.