Dr. Behrouz Zolfaghari

Watermarking is used in several areas such as CDNs (Content Delivery Networks), as part of the rights management system for counterfeit prevention. Watermarking schemes need some additional features in order to be used in digital cinema. In fact, extra watermarks are added to movies by cinema projectors in projection time, which help identify the cinema hall in which the illegal copy has been recorded. But distortions caused by hand vibrations and the point of view angle make it difficult to recover the watermark. This makes it necessary to be distortion-resistant for the watermarking schemes used in digital cinema. On the other hand, theatre owners would like to locate the camcorder that has recorded the pirate copy. This requires watermarking schemes to be able to estimate the distance and angle using the distributed pirate copy. In this chapter, we present a review on watermarking techniques specifically designed to attack the aforementioned problems.

CRC (Cyclic Redundancy Check) is used as an error detection code in Ethernet frames. This method attaches the residue of a modulo-2 division to the message in the sender side and recalculates the residue in the receiver side. The agreed-upon divisor is called the generator. The range of detectable errors in this method is determined by the properties of the generator. In this paper a systematic approach is proposed to identify all proper generators which can be used in Ethernet networks in order to detect double bit errors which invert a pair of bits in the message.