Fuzzy vault is the most practical scheme in bio-cryptosystems for the applications in protecting data in the real-world, error-prone environments. The biometric features were used to lock and unlock the secret key, which is encoded in the coefficients of a polynomial equation. The security of the fuzzy vault depends on the infeasibility of the polynomial reconstruction problem. The vault performance can be enhanced by adding more noise (chaff) points to the vault. The existing methods for generating chaff points were time consuming as producing more than 200 chaff points. This paper proposes a new chaff point generation technique for the fuzzy vault in bio-cryptosystems which is less time-consuming for producing more than 200 points. Complexity study shows that our algorithm has a complexity of O(n 2), which is a significant improvement over the existing algorithm of the complexity of O(n 3). Our experimental results show that the proposed algorithm achieves 14.84 and 41.86 times faster than Clancy's and Khalil-Hani's algorithms in the case of generating 240 chaff points. To generate the same numbers of valid chaff points, our proposed method needs less candidate points than the existing methods. Our proposed algorithm generates 11% more chaff points compared to the Khalil-Hani's algorithm.

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The fuzzy vault scheme is a well-known technique to protect the fingerprint templates and its secret key simultaneously in biometric systems. The performance of the fuzzy vault scheme is affected if collected fingerprint images are distorted. It is proved that ridge features of a fingerprint image have the advantage of being invariant to any geometric transformations. Therefore, the authors proposed a novel fingerprint fuzzy vault scheme based on ridge features information with the goal of improving its performance for distorted fingerprint images. They also proposed a novel noise generation technique to improve the security of the proposed fuzzy vault scheme. Experiments are carried on FVC2002 and FVC2004 databases, which include distorted fingerprint images. When the key size is 160 bit, the genuine accept rate is 89 and 75% with 0% false accept rate on FVC2002-DB2A and FVC2004-DB3A, respectively. Experimental results show that the proposed scheme achieves better performance than the existing methods. The security level of the proposed system is evaluated based on the min-entropy analysis and the degree of freedom of generated noise points. The security of their proposed fuzzy vault scheme is ∼42 bits. This proves that the proposed scheme maintains the security when dealing with distorted fingerprint images.

Through employing the solid-state process under significant temperature, we produced a sequence of single-element radiation-adjustable phosphors Ca8MgR(PO4)7:Eu 2+ ,Mn 2+ or CaMg:EM (R = La, Y), and thoroughly analyzed the crystalline arrangement, photoluminescence (PL), PL excitation (PLE), as well as the degrading period. The findings suggest that Ca8MgLa(PO4)7:Eu 2+ ,Mn 2+ could be a green contender to be used within close ultraviolet-chip white light-emitted diode (WLED) devices. It is possible to change the emitting green hue from Ca8MgLa1-xYx(PO4)7 treated with Eu 2+ to cyan by adjusting the La 3+ /Y 3+ proportion for the purpose of lowering the crystal field potency. Furthermore, power shift among Eu 2+ and Mn 2+ would be used to create a conventional one-stage white CaMg:EM having a CIE hue coordinate shown as (0.330, 0.328). The power transmission process was shown in the form of resonant dipole-quadrupole nature. In addition, we also computed the critical range. The white-emitting single-composition CaMg:EM was effectively coated above one close ultraviolet chip under 375 nm, indicating that it may become a strong choice of phosphor within close ultraviolet WLED devices.

The molten salt synthesis (MSS) method was used to effectively prepare green phosphors BaAl_1.4Si_0.6O_3.4N_0.6:Eu²⁺ (or BSON:Eu²⁺) via one homogeneous sphere-like morphology utilizing NaNO3 in the form of the reacting agent. The phosphors produced one wide stimulation spectrum between 250 and 460 nm, as well as a significant green emission has a maximum point at 510 nm owing to the 4f⁶5d¹-4f⁷ (⁸S_7/2) shifts for Eu²⁺ ions. With illumination under 365 as well as 450 nm, the ideal discharge strengths for the specimen prepared utilizing melted salt would receive a boost of 17% and 13%, surpassing the specimen prepared utilizing the traditional solid-state reaction (SSR) approach. The abatement of concentration for the ions of Eu²⁺ from BSON:Eu²⁺ is 5 mol%. In addition, the interactivity of dipole-dipole would be the cause of said abatement. Heat abatement would be studied utilizing the formation coordinate method with abatement temperature reaching ∼200 ^oC. Elemental mapping as well as power-dispersing X-ray spectroscopy (EDS) spectra demonstrated that the expected BaAl_1.4Si_0.6O_3.4N_0.6:Eu²⁺ materials were formed.