PASS: Privacy aware secure signature scheme for surveillance systems

In a surveillance system, the privacy becomes important since those who are not relevant to an event may be recorded by many surveillance systems. On the other hand, the authenticity of video frames in surveillance systems should be guaranteed if a video is used as evidence. Hence a signature is attached for each frame. However, it is contradictory to provide both privacy and authenticity of a video since the privacy requires deletion of objects in an original video image while the authenticity disallows any modification of the original image. This paper devises a new novel privacy aware secure signature scheme for the surveillance system. In the proposed scheme, deletion (or masking) of objects in an image is allowed while a signature still remains valid for the modified image. The proposed scheme utilizes a chameleon hash so that deletion of objects in an image does not invalidate the signature. The proposed scheme provides forward security minimizing the damage from the secret key exposure. The deletion is executed in an authorized way. Experimental results show that the proposed scheme is practical in a real-time video surveillance system due to the high performance of signature generation (40ms per frame) and a small signature size overhead (1%).