Prof. Roland Schmitz
Stuttgart Media University
Roland Schmitz has been a professor of Internet Security at Stuttgart Media University since 2001. He holds a diploma degree and a Ph.D. in mathematics, both from the technical university of Braunschweig, Germany. Before joining Stuttgart Media University, he worked as a senior researcher at the research center of Deutsche Telekom in Darmstadt, Germany, where he was concerned with mobile communications security, especially the UMTS security architecure, and digital signature standardization. At Stuttgart Media University, his research focused on multimedia and network security, and on usable security. He has authored or co-authored more than 70 peer-reviewed papers and several books. Since the beginning of 2026, he is also the Dean of the Master Program in Computer Science and Media at Stuttgart Media University.
Speech Title: "The Invariant Encryption Approach to Commutative Watermarking-Encryption"
Digital watermarks and encryption algorithms have been known to be important multimedia security primitives for many years. In a commutative watermarking-encryption (CWE) scheme, these primitives are combined so that the digital watermarks may be embedded into the cover media either in the encrypted or the plaintext domain. Likewise, the marks can be detected in the plaintext or ciphertext Domain, so that the order of the embedding and the encryption operation does not matter. In this talk possible usage scenarios for CWE schemes in buyer-seller scenarios or cloud computing are presented. We also discuss existing methods for implementing commutative watermarking-encryption and their relative merits, with a special focus on the so-called invariant encryption approach, where the watermark is embedded into some feature space left invariant by the encryption operation. As an outlook, we will sketch a possible way to integrate recent, machine-learning-based watermarking methods into a commutative watermarking-encryption scheme using the invariant encryption approach.