1,118 research outputs found
Software watermarking using fixed size encoding and random dummy method insertion
The rise of software piracy has become rampant and a major concern among software developers. One of the techniques that can be used to discourage piracy is watermarking, by embedding developer’s watermark into software which can later be extracted to prove ownership. During the last few years, different algorithms were produced and developed to hide the watermark inside software. This paper enhances dummy method insertion technique in embedding and recognizing the watermark in Java class files. The enhancement includes the use of fixed size encoding scheme and random dummy method insertion. The proposed fixed size encoding scheme used hash function that can produce a fixed size watermark bit sequences. Random dummy method insertion selects a dummy method from a collection of dummy methods randomly. Finally, this study analyzes the enhancement of dummy method insertion technique using two different measures, namely data-rate and resilience of the watermarking algorithm. In terms of data rate, the results show that encoded watermark for proposed encoding scheme is always fixed even though size of watermark character is increased. In terms of resilience, experimental results show no similarity between class files and thus survived from collusion attack compared to previous method
Fast watermarking of MPEG-1/2 streams using compressed-domain perceptual embedding and a generalized correlator detector
A novel technique is proposed for watermarking of MPEG-1 and MPEG-2 compressed video streams. The proposed scheme is applied directly in the domain of MPEG-1 system streams and MPEG-2 program streams (multiplexed streams). Perceptual models are used during the embedding process in order to avoid degradation of the video quality. The watermark is detected without the use of the original video sequence. A modified correlation-based detector is introduced that applies nonlinear preprocessing before correlation. Experimental evaluation demonstrates that the proposed scheme is able to withstand several common attacks. The resulting watermarking system is very fast and therefore suitable for copyright protection of compressed video
Robust error detection methods for H.264/AVC videos
The 3rd generation of mobile systems is mainly focused on enabling multimedia
services such as video streaming, video call and conferencing. In order to achieve
this, the Universal Mobile Telecommunications System (UMTS), is the standard that
has been developed by the 3rd Generation Partnership ect (3GPP) in Europe,
including the baseline profile of H.264/AVC in the specification. With the union of
both technologies a great improvement on video transmission over mobile networks,
and even modification of the user habits towards the use of the mobile phone is expected.
Nevertheless, video transmission has always been related to wired networks
and unfortunately the migration to wireless networks is not as easy as it seems.
In real time applications the delay is a critical constraint. Usually, transmission
protocols without delivery warranties, like the User Network Protocol (UDP) for IP
based networks, are used. This works under the assumption that in real time applications
dropped packets are preferable to delayed packets. Moreover, in UMTS the
network needs to be treated in a different way, thus the wireless channel is a prone
error channel due to its high time variance. Typically, when transmitting video, the
receiver checks whether the information packet is corrupted (by means of a checksum)
or if its temporal mark exceeds the specified delay. This approach is suboptimal, due to the fact that
perhaps the video information is not damaged and could still be used.
Instead, residual redundancy on the video stream can be used to locate the errors
in the corrupted packet, increasing the granularity of the typical upper-layer checksum
error detection. Based on this, the amount of information previous to the error
detection can be decoded as usually.
The aim of this thesis is to combine some of the more effective methods concretely, Syntax check, Watermarking and Checksum schemes have
been reformulated, combined and simulated
Models and Algorithms for Graph Watermarking
We introduce models and algorithmic foundations for graph watermarking. Our
frameworks include security definitions and proofs, as well as
characterizations when graph watermarking is algorithmically feasible, in spite
of the fact that the general problem is NP-complete by simple reductions from
the subgraph isomorphism or graph edit distance problems. In the digital
watermarking of many types of files, an implicit step in the recovery of a
watermark is the mapping of individual pieces of data, such as image pixels or
movie frames, from one object to another. In graphs, this step corresponds to
approximately matching vertices of one graph to another based on graph
invariants such as vertex degree. Our approach is based on characterizing the
feasibility of graph watermarking in terms of keygen, marking, and
identification functions defined over graph families with known distributions.
We demonstrate the strength of this approach with exemplary watermarking
schemes for two random graph models, the classic Erd\H{o}s-R\'{e}nyi model and
a random power-law graph model, both of which are used to model real-world
networks
Content Fragile Watermarking for H.264/AVC Video Authentication
Discrete Cosine transform (DCT) to generate the authentication data that are treated as a fragile watermark. This watermark is embedded in the motion vectors (MVs) The advances in multimedia technologies and digital processing tools have brought with them new challenges for the source and content authentication. To ensure the integrity of the H.264/AVC video stream, we introduce an approach based on a content fragile video watermarking method using an independent authentication of each Group of Pictures (GOPs) within the video. This technique uses robust visual features extracted from the video pertaining to the set of selected macroblocs (MBs) which hold the best partition mode in a tree-structured motion compensation process. An additional security degree is offered by the proposed method through using a more secured keyed function HMAC-SHA-256 and randomly choosing candidates from already selected MBs. In here, the watermark detection and verification processes are blind, whereas the tampered frames detection is not since it needs the original frames within the tampered GOPs. The proposed scheme achieves an accurate authentication technique with a high fragility and fidelity whilst maintaining the original bitrate and the perceptual quality. Furthermore, its ability to detect the tampered frames in case of spatial, temporal and colour manipulations, is confirmed
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