This paper presents a new segmentation-based method for generating high-quality monochromatic images of historical documents. The proposed segmentation algorithm is based on the entropy of the histogram of the image. The algorithm eliminates back-to-front interference in documents written on both sides on translucent paper.
This paper introduces a new multi-instance key regeneration system used to regenerate cryptographic keys from biometric data. The serial concatenation of Reed-Solomon and Hadamard codes together with the use of a single extra mechanism and biometrics improve the biometric performance and security of the system, also making it possible the regeneration of longer and higher entropy cryptographic keys. The system was evaluated on two public databases: Casia-Biosecure and NIST-ICE 2005 and it provided a complete separation between the Hamming distance distributions for genuine users and impostors, respectively, being able to achieve both false acceptance rate (FAR) and false rejection rate (FRR) of 0%. Furthermore, on NIST-ICE 2005 it is possible to regenerate a 287 binary digit cryptographic key with estimated entropy of 160 bits at 0% FAR and 0.34% FRR.
A class of p-ary (n, k, d) cyclic codes with block length n = p, dimension k = 2 and minimum Hamming distance d = n − k + 1 = p − 1 is introduced, where p denotes a prime. These codes are maximum distance separable repeated-single-root cyclic codes with generator polynomial g(x) = (x-1) p-2. The codebook has size p 2 and contains a subset S of p(p-1)codewords having p distinct symbols each. The size of S is maximum for the given parameters and its codewords are useful for applications of coded modulation in power-line communications.
A new test called rotation search is proposed for user identification and cryptographic key regeneration in systems employing a digital representation of the iris which is called the iris code. When applied to the BIOSECURE, CASIA and NIST-ICE data bases the rotation search shows, on average, a two fold reduction in false rejection ratio (FRR) with a false acceptance ratio (FAR) equal to zero, in comparison with the standard search employed in other systems. The highest improvement reached in FRR by the rotation search against the standard search is about 100 times for a single iris and 85 times for the two irides of a user, and in many cases the measured FRR is equal to zero. . Prof. da Rocha research interests are in applied digital information theory, including error-correcting codes and cryptography. He has published over 100 engineering and scientific papers, including journal and conference papers, and the books Communication Systems, Springer, 2005, and Elements of Algebraic Coding Systems, Momentum Press, 2014. He is currently a Member of the IEEE Alexander Graham Bell Medal Committee.
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