Enables identification and detection of processing and type of digital content, while using multiple electronic watermarks. One embodiment provides a data processing detection system having an embedding apparatus for adding a predetermined additional signal to digital content, including a watermark design unit and embedding signal generators for generating multiple types of additional signals, correlated with each other and of differing robustness from each other for the processing of the content data, and a synthesis unit for adding the multiple types of additional signals to the content data; and detection apparatus for detecting additional signals in the digital content, and for detecting the additional signals embedded by the embedding apparatus, including an individual detector for detecting in the content data multiple additional signals, and a determination unit for examining deterioration levels of the additional signals to determine the type of processing performed for the content data.