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NTRUEncrypt is a public key cryptosystem based on hard problems over lattices. The dominant operation in NTRUEncrypt is convolution, i.e., multiplication over a quotient ring of polynomials. Based on the fact that a convolution has a highly regular structure, Lee et al. proposed the sliding window method for fast convolution of binary polynomials in 2013, which was then extended to ternary polynomials for ideal lattices by Akleylek, Alkim, and Tok in 2016. These sliding window methods reduce the cost of a convolution operation using look-up tables that store partial computation results related to repeated coefficient patterns. In this paper, we propose a signed sliding window method with side-channel resistance for NTRUEncrypt. The proposed method considers both positive and negative nonzero coefficients when constructing look-up tables. The new method not only accelerates convolution but also enables the application of power analysis countermeasures effectively. According to the experimental results, the constant-time implementation of the proposed method with timing and power analysis countermeasures accelerates the previously developed secure convolution method by up to 20%.

The biggest cause of the epidemic is “unpredictable.” In Korea, the number of patients with hepatitis A has been increasing recently, and the government enacted a law in 1954 to effectively manage diseases such as hepatitis A. The purpose of this paper is to design a model for predicting trends in order to minimize the damage caused by the prevalence of infectious diseases. As a tool for it, various statistical techniques and Supervised Learning of Machine Learning and LSTM techniques were used. To this end, data were collected using Web Crawling and other data, correlation analysis using Regression analysis was conducted, and prediction models were designed using Machine Learning and LSTM.

Biometric verification systems have security issues regarding the storage of biometric data in that a user's biometric features cannot be changed into other ones even when a system is compromised. To address this issue, it may be safe to store the biometrics data on a reliable remote server instead of storing them in a local device. However, this approach may raise a privacy issue. In this paper, we propose a biometric verification system where the biometric data are stored in a remote server in an encrypted form and the similarity of the user input to the registered biometric data is computed in an encrypted domain using a homomorphic encryption. We evaluated the performance of the proposed system through an implementation on an Android-based smartphone and an i7-based server.

Passwords and PINs are convenient and ubiquitous, yet they are quite vulnerable to attackers who stand near the user. This problem may be partially resolved by changing the user interface, but previous solutions of this kind still give shoulder-surfing attackers a significant advantage over brute-force search. We propose a novel solution based on 3D, especially suitable for glasses-free 3D displays found in many smartphones and handheld game consoles. A user at the “3D spot” may log in easily, while nearby shoulder-surfers gain no advantage. We perform a detailed experimental analysis of the usability of our scheme.

We propose a user authentication method that uses a smart phone as a hardware token. Our method enables a smart phone to prove its owner's identity by receiving audio challenges from a target system.

We propose a novel authentication method that uses smart phones and 2-D barcodes. Using our method, a user can access a system by just taking a picture of a challenge code displayed in the target system.

Personal identification number (PIN) is a common user authentication method widely used for ATMs and mobile phones. However, an attacker can obtain the PIN easily by looking over a user's shoulder. We present a new PIN entry method which makes this kind of attack significantly harder.

User authentication is a mechanism that enables a user of a system to prove his identity and to have access to the system. Traditionally, there are three categories of authentication mechanisms based on what we know, what we are, and what we have. In this paper, we show some possible weaknesses in the third class of schemes and we propose a new user authentication scheme based on distance estimation using ultrasonic communication.

Recently, Mukherjee, Ganguly, and Chaudhuri proposed a message authentication scheme using a special class of cellular automata called Single Attractor Cellular Automata (SACA). In this paper, we show that their scheme is vulnerable to a chosen-message attack, i.e., the secret key can be recovered by an attacker using only several chosen message-MAC pairs. The weakness of the scheme results from the regularity of SACA.