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Systems of technical information security |Системы технической защиты информации

LESSON 1

Read the text: An efficient and secure robust watermarking scheme for document images using Integer wavelets and block coding of binary watermarks

 A novel, efficient and robust watermarking scheme for protection of document image contents is proposed in this work. An integer wavelet-based watermarking scheme for embedding the compressed version of the binary watermark logo has been developed for robust watermarking. At the sender side, the source document image is divided into empty and non-empty segments depending on the absence or presence of the information. Watermarking is applied for non-empty segments and thus the amount of embedding capacity is reduced. A binary watermark logo is compressed using binary block coding technique of appropriate block-size. A level-2 integer wavelet transformation is applied on the non-empty segment of the source document image. LL-sub-band of level-2 of the transformed image is subdivided into blocks of uniform size and compressed watermark bitstream is embedded into it. The compressed watermark is redundantly embedded into blocks using quantization technique. Thus, multiple copies of compressed watermark are available and each block of the source document image segment need not include the entire compressed watermark stream. At the receiver side, the extracted segments from each set of blocks are merged to obtain a single extracted bitstream. The bitstream is further decoded to get the binary watermark. The extracted and embedded watermarks are compared and authentication decision is taken based on majority voting technique. Based on the quantization step size, size of the logo and the level of wavelet transform, the watermarks are extracted without accessing the original image. The experimental results show that the proposed technique is highly robust. The performance of the proposed approach is measured in parameters Peak Signal to Noise Ratio (PSNR) and Normalized Correlation Coefficient (NCC). Results show that the proposed approach is better than the existing methods. In the proposed scheme for decompression of watermark, the level of block coding technique is the key, which provides an additional layer of security.

 Cross-domain collaboration for improved IDS rule set selection

Managing an intrusion detection system (IDS) requires careful consideration of the IDS rule set used to match malicious traffic. Network operators face a tradeoff when selecting rules: a rule set that is too conservative (too few rules) could lead to network intrusion and attacks from unforeseen risks, while a rule set that is too broad (too many rules) runs the risk of increasing false alerts and diminishing network throughput. The ultimate goal is to deploy rules that are conservative but proactive, and optimizing and testing such a rule set can be time consuming and limited when considering only locally observed network traffic. We argue that automated techniques to compare feedback from multiple collaborating sources, such as collaborative filtering between networks, can improve local rule sets. Our system, ROCK (Rule set Optimization via Collaborative Knowledge), recommends network-specific, locally untested rules to network operators based on correlations between their feedback and previously submitted feedback from other operators. We evaluated ROCK in two experimental deployments to detect shellcode and in simulation to measure the effect of broad collaboration. Network operators benefitted even if they provided feedback ratings for as few as 5 rules and deployed only the top 5 rules that ROCK recommended for their network; shellcode detection rates increase by up to 150% over a local baseline with little to no impact on false alerts. Our simulation analysis suggests that ROCK's recommendation quality increases rapidly with the number of user networks and can leverage varied degrees of similarity across networks. Our results demonstrate how security through collaboration can benefit local networks and provide proactive security in an automated way.

1. Match the left part with the right:

2. Complete the sentences with the suggested words:

 amount   applied   the   watermark

Watermarking is (1)_________ for non-empty segments and thus the (2)_________ of embedding capacity is reduced. A binary (3)_________ logo is compressed using binary block coding technique of appropriate block-size. A level-2 integer wavelet transformation is applied on (4)_________ non-empty segment of the source document image.