The present invention relates to a method, computer program product and a device for detecting watermarks in digital data for the purpose of electronic copyright management system. The invention includes transforming the original as well as unwatermarked data. Thereafter, tagging the resultant components of the transformed data using a pair of rows and columns. Then, selecting significant components in the said transformed data, transforming the suspected watermarked data and tagging the components in the transformed data. Further, selecting the tagged components from the transformed suspected watermarked data corresponding to those selected as significant in the original transformed data, and comparing said two groups of selected significant components to detect the watermarks.