Security camera video authentication

The ability to authenticate images captured by a security camera, and localise any tampered areas, will increase the value of these images as evidence in a court of law. This paper outlines the challenges in security camera video authentication, and discusses the reasons why fingerprinting, a robust type of digital signature, provides a solution preferable to semi-fragile watermarking. A fingerprint based upon block DC differences is described, and the tamper detection performance is assessed both theoretically and experimentally, the latter using an automated method of ´tampering´ images.