Ensuring Media Integrity on Third-Party Infrastructures

In many heterogeneous networked applications the integrity of multimedia data plays an essential role, but is not directly supported by the application. In this paper, we propose a method which enables an individual user to detect tampering with a multimedia file without changing the software application provided by the third party. Our method is based on a combination of cryptographic signatures and fragile watermarks, i.e., watermarks that are destroyed by illegitimate tampering. We show that the proposed system is provably secure under standard cryptographic assumptions.