Distortion-Aware Multimedia Authentication using an Enhanced Hash Function

A new type of hash function called the distance preserving (DP) hash function is proposed to tackle the shortcoming of the traditional bit-wise multimedia authentication scheme. A DP hash function accepts two inputs: the message and a security key. It is indistinguishable from a conventional hash function under different security keys. However, if the same security key is applied, the DP hash function yields the distance information between the original and the distorted inputs. In other words, the distortion is only accessible to legitimate users knowing the correct key and will not be revealed to any unauthorized party. We study the properties of the DP hash function and provide an example for its construction. A generalized framework for distortion-aware multimedia authentication using the DP hash function is proposed where users can evaluate the content distortion and render the authenticity degree. Experiments are conducted to demonstrate the effectiveness of the DP hash function for multimedia authentication