• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.5
• /
• pp.1001-1008
• /
• 2019

A high-quality pseudorandom sequence generation is an important part of many cryptographic applications, including encryption protocols. Therefore, a pseudorandom number generator (PRNG) is an essential element for generating key sequences in a cryptosystem. A PRNG must effectively generate a large, high-quality random data stream. It is well known that the bitstreams output by the CA-based PRNG are more random than the bitstreams output by the LFSR-based PRNG. In this paper, we prove that the complemented CA derived from 90/150 maximum length cellular automata(MLCA) is a MLCA to design a PRNG that can generate more secure bitstreams and extend the key space in a secret key cryptosystem. Also we give a method for calculating the cell positions outputting a nonlinear sequence with maximum period in complemented MLCA derived from a 90/150 MLCA and a complement vector.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.12 no.2
• /
• pp.240-253
• /
• 2012

In this paper we propose a protection mechanism for the debug port. While debug ports are useful tools for embedded device development and maintenance, they can also become potential attack tools for device hacking in case their usage is permitted to hackers with malicious intentions. The proposed approach prevents illicit use of debug ports by controlling access through user authentication, where the device generates and issues authentication token only to the server-authenticated users. An authentication token includes user access information which represents the user's permitted level of access and the maximum number of authentications allowed using the token. The device authenticates the user with the token and grants limited access based on the user's access level. The proposed approach improves the degree of overall security by removing the need to expose the device's secret key. Availability is also enhanced by not requiring server connection after the initial token generation and further by supporting flexible token transfer among predefined device groups. Low implementation cost is another benefit of the proposed approach, enabling it to be adopted to a wide range of environments in demand of debug port protection.

• Journal of Korea Multimedia Society
• /
• v.20 no.12
• /
• pp.1928-1939
• /
• 2017

Fog computing is another paradigm of the cloud computing, which extends the ubiquitous services to applications on many connected devices in the IoT (Internet of Things). In general, if we access a lot of IoT devices with existing cloud, we waste a huge amount of bandwidth and work efficiency becomes low. So we apply the paradigm called fog between IoT devices and cloud. The network architecture based on cloud and fog computing discloses the security and privacy issues according to mixed paradigm. There are so many security issues in many aspects. Moreover many IoT devices are connected at fog and they generate much data, therefore light and efficient security mechanism is needed. For example, with inappropriate encryption or authentication algorithm, it causes a huge bandwidth loss. In this paper, we consider issues related with data encryption and authentication mechanism in the network architecture for cloud and fog-based M2M (Machine to Machine) IoT services. This includes trusted encryption and authentication algorithm, and key generation method. The contribution of this paper is to provide efficient security mechanisms for the proposed service architecture. We implemented the envisaged conceptual security check mechanisms and verified their performance.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.4
• /
• pp.2292-2309
• /
• 2017

Ciphertext policy attribute-based encryption (CP-ABE) is a useful cryptographic technology for guaranteeing data confidentiality but also fine-grained access control. Typically, CP-ABE can be divided into two classes: small universe with polynomial attribute space and large universe with unbounded attribute space. Since the learning with errors over rings (R-LWE) assumption has characteristics of simple algebraic structure and simple calculations, based on R-LWE, we propose a small universe CP-ABE scheme to improve the efficiency of the scheme proposed by Zhang et al. (AsiaCCS 2012). On this basis, to achieve unbounded attribute space and improve the expression of attribute, we propose a large universe CP-ABE scheme with the help of a full-rank differences function. In this scheme, all polynomials in the R-LWE can be used as values of an attribute, and these values do not need to be enumerated at the setup phase. Different trapdoors are used to generate secret keys in the key generation and the security proof. Both proposed schemes are selectively secure in the standard model under R-LWE. Comparison with other schemes demonstrates that our schemes are simpler and more efficient. R-LWE can obtain greater efficiency, and unbounded attribute space means more flexibility, so our research is suitable in practices.

• Journal of Korea Multimedia Society
• /
• v.16 no.12
• /
• pp.1413-1426
• /
• 2013

RFID thecnology has been widely adopted by industries for supply chain management. When a product item is manufactured RFID tag is attached to the product item and supply chain management among factories, distributors, retailers and customers needs to handle ownership transfer for the product item carefully. With RFID technology, the secure and efficient ownership transfer protocol is an important issue for the identification of product items and the overall system efficiency on supply chain. Many ownership transfer protocols have been proposed now. They have security problems and use complex operations such as encryption operation and hash function. Lo et al. proposed a protocol using lightweight operations such as shift, addition, XOR, and random number generation[1]. However, this protocol has a security problem in which the secret key between the tag and the new owner is disclosed to the attackers, and it is also weak against the Fraud attack[2]. In this paper, we propose a new ownership transfer protocol using lightweight operations such as shift, addition, and random number generation. This protocol is the modified version of Lo et al.'s protocol and is secure against the security attacks.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.26 no.2
• /
• pp.335-344
• /
• 2016

It is known that power analysis is one of the most powerful attack in side channel analysis. Among power analysis single trace attack is widely studied recently since it uses one power consumption trace to recover secret key of public cryptosystem. Recently Sim et al. proposed new exponentiation algorithm for RSA cryptosystem with higher attack complexity to prevent single trace attack. In this paper we analyze the vulnerability of exponentiation algorithm described by Sim et al. Sim et al. applied message blinding and random exponentiation splitting method on $2^t-ary$ for higher attack complexity. However we can reveal private key using information exposed during pre-computation generation. Also we describe modified algorithm that provides higher attack complexity on collision attack. Proposed algorithm minimized the reuse of value that are used during exponentiation to provide security under single collision attack.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.29 no.2
• /
• pp.261-273
• /
• 2019

Recently, with the development of IT technology, there is an increasing interest in cloud services as the number of users using mobile devices such as mobile phones and tablets is increasing. However, there is a need for techniques to control or control various methods of accessing data as the user's service demands increase. In this paper, we propose a dual key based user authentication model that improves the user 's authentication efficiency by using two keys (secret key and access control key) to access the users accessing various services provided in the cloud environment. In the proposed model, the operation process and the function are divided through the sequence diagram of the algorithms (key generation, user authentication, permission class permission, etc.) for controlling the access right of the user with dual keys. In the proposed model, two keys are used for user authentication and service authorization class to solve various security problems in the cloud service. In particular, the proposed model is one of the most important features in that the algorithm responsible for access control of the user determines the service class of the user according to the authority, thereby shortening the management process so that the cloud administrator can manage the service access permission information of the user.

• Journal of KIISE:Computer Systems and Theory
• /
• v.35 no.4
• /
• pp.172-177
• /
• 2008

In this paper, we design an authentication protocol based on Fuzzy Signature Vault Scheme using a light signature feature extraction method for user convenience and efficiency of electronic commerce. The signature is used broadly in electronic commerce because it is one of the simple and low-cost biometric items. However, signature has a problem that there are few low-cost and safe protocols. To solve this problem, we design a feature extraction method which is adequate for characters of signature and Fuzzy Vault Scheme. In addition, we design and analyze an efficient authentication protocol with some parameters used in this procedure. The followings are advantages when this protocol is applied to authentication procedure; 1) using convenient and low-cost signatures, 2) being possible to verify users with spending only about second for signature processing and authentication, 3) one time on transmission for sign-in and verification and 4) getting user authentication with secret value at the same time.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.27 no.2
• /
• pp.373-381
• /
• 2017

Currently, various types of user authentication methods based on public certificates are used in domestic financial transactions. Such an authorized certificate method has a problem that a different security module must be installed every time a user connects an individual financial company to a web server. Also, the financial company relying on this authentication method has a problem that a new security module should be additionally installed for each financial institution whenever a next generation authentication method such as biometric authentication is newly introduced. In order to solve these problems, we propose an integrated authentication system that handles user authentication on behalf of each financial institution in financial transactions, and proposes an integrated authentication protocol that handles secure user authentication between user and financial company web server. The new authentication protocol is a modified version of OAuth2.0 that increases security and efficiency. It is characterized by performing a challenge-response protocol with a pre-shared secret key between the authentication server and the financial company web server. This gives users a convenient and secure Single Sign-On (SSO) effect.

• Convergence Security Journal
• /
• v.22 no.3
• /
• pp.33-39
• /
• 2022

Recently, cyberattacks on infrastructure have been continuously occurring with the starting of neutralizing the user authentication function of information systems. Accordingly, the vulnerabilities of system are increasing day by day, such as the increase in the vulnerabilities of the encryption system. In this paper, an alternative technique for the symmetric key algorithm has been developed in order to build the encryption algorithm that is not easy for beginners to understand and apply. Vigenere Cipher is a method of encrypting alphabetic text and it uses a simple form of polyalphabetic substitution. The encryption application system proposed in this study uses the simple form of polyalphabetic substitution method to present an application model that integrates the three steps of encryption table creation, encryption and decryption as a framework. The encryption of the original text is done using the Vigenère square or Vigenère table. When applying to the automatic generation of secret keys on the information system this model is expected that integrated authentication work, and analysis will be possible on target system. ubstitution alphabets[3].