Lorenz System Parameter Determination and Application to Break the Security of Two-channel Chaotic Cryptosystems

This paper describes how to determine the parameter values of the chaotic Lorenz system used in a two-channel cryptosystem. The geometrical properties of the Lorenz system are used firstly to reduce the parameter search space, then the parameters are exactly determined, directly from the ciphertext, through the minimization of the average jamming noise power created by the encryption process.Comment: 5 pages, 5 figures Preprint submitted to IEEE T. Cas II, revision of authors name spellin

An investigation of horizontal transfer of feed introduced DNA to the aerobic microbiota of the gastrointestinal tract of rats

Background: Horizontal gene transfer through natural transformation of members of the microbiota of the lower gastrointestinal tract (GIT) of mammals has not yet been described. Insufficient DNA sequence similarity for homologous recombination to occur has been identified as the major barrier to interspecies transfer of chromosomal DNA in bacteria. In this study we determined if regions of high DNA similarity between the genomes of the indigenous bacteria in the GIT of rats and feed introduced DNA could lead to homologous recombination and acquisition of antibiotic resistance genes. Results: Plasmid DNA with two resistance genes (nptII and aadA) and regions of high DNA similarity to 16S rRNA and 23S rRNA genes present in a broad range of bacterial species present in the GIT, where constructed and added to standard rat feed. Six rats, with a normal microbiota, were fed DNA containing pellets daily over four days before sampling of the microbiota from the different GI compartments (stomach, small intestine, cecum and colon). In addition, two rats were included as negative controls. Antibiotic resistant colonies growing on selective media were screened for recombination with feed introduced DNA by PCR targeting unique sites in the putatively recombined regions. Conclusions: The analyses showed that extensive ingestion of DNA (100 \ub5g plasmid) per day did not lead to increased proportions of kanamycin resistant bacteria, nor did it produce detectable transformants among the aerobic microbiota examined for 6 rats (detection limit <1 transformant per 1.1 x 108 cultured bacteria). The key methodological challenges to HGT detection in animal feedings trials are identified and discussed

A new parameter determination method for some double-scroll chaotic systems and its applications to chaotic cryptanalysis

This paper describes a method about how to determine parameters of some double-scroll chaotic systems, including the Lorenz system and the Chua’s circuit, from one of its variables. The geometric properties of the system are exploited firstly to reduce the parameter search space. Then, a synchronization-based approach, with the help of the same geometric properties as coincidence criteria, is implemented to determine the parameter values with the wanted accuracy. The method is not affected by a moderate amount of noise in the waveform. As an example of its effectiveness, the method is applied to cryptanalyze two two-channel chaotic cryptosystems, figuring out how the secret keys can be directly derived from the driving signal z(t)

Determination of the parameters for a Lorenz system and application to break the security of two-channel chaotic cryptosystems

This Letter describes how to determine the parameter of the chaotic Lorenz system used in a two-channel cryptosystem. First the geometrical properties of the Lorenz system are used to reduce the parameter search space. Second the parameters are exactly determined—directly from the ciphertext—through the minimization of the average jamming noise power created by the encryption process