arXiv subjects

Manabu Inuma

Publications and source records attributed to Manabu Inuma.

3 recordsLinked to original sources

arXiv2026

Degree shifts between q-deformed friezes and q-Farey labelings for general triangulations

Morier-Genoud and Ovsienko introduced q-deformations of continued fractions, Farey labelings, and Conway--Coxeter friezes, and established relationships among them in restricted settings associated with triangulations having exactly two exterior cells. In this paper, we extend these correspondences to arbitrary subsequences of quiddities arising from general triangulations. We show that the numerator and denominator polynomials of q-deformed continued fractions coincide with entries of q-deformed Conway--Coxeter friezes, while the corresponding polynomials in q-Farey labelings agree with them up to explicit powers of q. These powers are described combinatorially in terms of the number of diagonals in the triangulation, or equivalently, the number of entries equal to 1 in the associated frieze. Furthermore, we determine the minimum and maximum degrees of these polynomials in terms of the same combinatorial data.

math.CO↗

arXiv2013

Relations among Security Metrics for Template Protection Algorithms

Many biometric template protection algorithms have been proposed mainly in two approaches: biometric feature transformation and biometric cryptosystem. Security evaluation of the proposed algorithms are often conducted in various inconsistent manner. Thus, it is strongly demanded to establish the common evaluation metrics for easier comparison among many algorithms. Simoens et al. and Nagar et al. proposed good metrics covering nearly all aspect of requirements expected for biometric template protection algorithms. One drawback of the two papers is that they are biased to experimental evaluation of security of biometric template protection algorithms. Therefore, it was still difficult mainly for algorithms in biometric cryptosystem to prove their security according to the proposed metrics. This paper will give a formal definitions for security metrics proposed by Simoens et al. and Nagar et al. so that it can be used for the evaluation of both of the two approaches. Further, this paper will discuss the relations among several notions of security metrics.

cs.CR↗

arXiv2009

Theoretical framework for constructing matching algorithms in biometric authentication systems

In this paper, we propose a theoretical framework to construct matching algorithms for any biometric authentication systems. Conventional matching algorithms are not necessarily secure against strong intentional impersonation attacks such as wolf attacks. The wolf attack is an attempt to impersonate a genuine user by presenting a "wolf" to a biometric authentication system without the knowledge of a genuine user's biometric sample. A wolf is a sample which can be accepted as a match with multiple templates. The wolf attack probability (WAP) is the maximum success probability of the wolf attack, which was proposed by Une, Otsuka, Imai as a measure for evaluating security of biometric authentication systems. We present a principle for construction of secure matching algorithms against the wolf attack for any biometric authentication systems. The ideal matching algorithm determines a threshold for each input value depending on the entropy of the probability distribution of the (Hamming) distances. Then we show that if the information about the probability distribution for each input value is perfectly given, then our matching algorithm is secure against the wolf attack. Our generalized matching algorithm gives a theoretical framework to construct secure matching algorithms. How lower WAP is achievable depends on how accurately the entropy is estimated. Then there is a trade-off between the efficiency and the achievable WAP. Almost every conventional matching algorithm employs a fixed threshold and hence it can be regarded as an efficient but insecure instance of our theoretical framework. Daugman's IrisCode recognition algorithm proposed can also be regarded as a non-optimal instance of our framework.

cs.CR↗