Earticle

다중서버 환경에서 인가된 사용자만이 서버의 데이터와 서비스들을 이용할 수 있어야 함으로 인증된 키 동의는 보안 이슈들 중에서 가장 중요한 문제 중 하나이다. 이러한 보안 이슈를 지원하기 위해서 다양한 기법들이 최근 몇 년간 제안되었다. 특히, 최근에 Shin은 기존 기법의 보안 문제점을 도출하고 이를 해결할 수 있는 개선된 기법인 SIAKAS를 제안하였다. 본 논문에서는 SIAKAS가 여전히 응용서버 가장 공격에 취약하고 추적성을 제공하는 문제가 있음을 보이고, 이러한 문제들을 해결할 수 있는 비추적성을 제공하는 인증된 키 동의 기법인 UAKAS를 제안한다. UAKAS는 SIAKAS 및 관련된 기법들의 보안 및 프라이버시 문제를 해결하고 이들에 비해서 최소 12%의 연산 오버헤드를 줄일 수 있는 장점이 있다.

Authenticated key agreement in multi-server environments is one of very important security issues because only authorized user needs to access their data and services. To support this issue, numerous schemes have been proposed over recent years. Recently, Shin showed the security weaknesses in the previous scheme and proposed an improved scheme called SIAKAS to solve them. Unfortunately, this paper shows that SIAKAS is still weak against application server impersonation attack and could be traceable to attackers. To solve the problems in SIAKAS, we propose an untraceable authenticated key agreement scheme, denoted by UAKAS. UAKAS efficiently solves security and privacy issues in SIAKAS and the related schemes and could reduce the operation overhead at least 12% compared to them.

본 논문은 고속도로 톨게이트에서 통행 요금징수로 인해 교통지체가 발생할 때 이를 최소화하기 위해 자동요금징수시스템을 설치하는 경우 차량들의 통과시간이 어떻게 변화하는지 분석한 연구결과를 제시하고 있다. 본 연구에서는 이 설치효과를 톨게이트를 빠져나가는 차량들의 통과시간 감소 편익이라고 생각했으며, 차량의 통과시간을 분석하기 위해 다중서비스 대기행렬이론을 적용해서 분석하였다. 본 연구에서 분석한 결과, 톨게이트로 진입하는 차량들의 입차 간격이 Poisson 분포를 따르고, 자동요금징수시스템의 서비스 시간이 지수 분포를 따를 때 다중서비스 대기행렬이론을 적용하여 차량들의 통과시간을 분석하는 것이 바람직하다는 것과, 자동요금징수시스템을 설치하더라도 통행 요금을 징수하는데 걸리는 시간이 다르기 때문에 톨게이트 출구 쪽이 입구 쪽보다 통과시간 감소효과가 더 크게 나타난다는 것, 그리고 자동요금징수시스템을 설치한다고 해서 항상 톨게이트를 통과하는 시간이 감소하는 것은 아니며, 자동요금징수시스템 차로에 너무 많은 차량들이 몰리는 경우 오히려 톨게이트 전체로 볼 때는 차량당 통과시간이 증가한다는 것을 밝혔다. 끝으로 본 연구에서는 다중서비스 대기행렬이론의 정확성을 판단하기 위해 실제로 톨게이트 현장조사에서 통과 차량들의 평균 통과시간을 조사해서 모형 값과 비교했는데, 그 결과 모형 값과 실측 값은 약 1~3초 정도의 미소한 차이만을 보여서 다중서비스 대기행렬이론을 실무에 적용해도 좋다는 결론을 얻었다.

This paper presents the investigation results of a research on how engineers can analyze the economic effect of the ETCS(Electronic Toll Collection System) installed to minimize the vehicle delays on freeway tollgates during toll payments. This research considered this economic effect to occur in the form of vehicle passing time reductions at the ETCS, and the multi-service queuing theory was applied to estimate these values. This research found: 1) When vehicles approaching tollgates show Poisson distribution and the service time of the ETCS shows Exponential distribution, the multi-service queuing theory would be applicable for estimating vehicle passing times at toll-gates, 2) Despite the ETCS placement, exit sections of tollgates give a greater reduction of vehicle passing times than entering sections due to more delays at conventional toll payments, and 3)The ETCS would not guarantee vehicle passing time reductions all the time, because in such a case as many vehicles were queuing at the ETCS, the total delay level for a toll gate would increase greatly. In addition, in order to examine the accuracy of the estimated vehicle passing values, this research compared the values from the multi-service queuing theory with the observed values from a set of field survey values at freeway toll-gates, and found that the two values were in a good agreement with a very low error range of 1-3 seconds per vehicle. Based on this result, the multi-service queuing theory was recommended for practice.

많은 기업과 단체들은 원격 접근을 위해 스마트카드 기반 사용자 인증을 사용한다. 그 동안 다양한 연구를 통하여 사용자 와 서버 간의 연결을 보호하기 위해 분산된 다중 서버 환경에 대한 동적 ID 기반 원격 사용자 인증 프로토콜들이 제안되었다. 그 중, Qiu 등은 상호 인증 및 키 동의, 사용자 익명성, 다양한 종류의 공격에 대한 저항을 제공하는 효율적인 스마트카드 기 반 원격 사용자 인증 프로토콜을 제안하였다. 이후, Andola 등은 Qiu 등이 제안된 인증 프로토콜에 대한 다양한 취약점을 찾 아내었고, 그들의 인증 프로토콜에 대한 결점을 극복하고 사용자가 서버에 로그인하기를 원할 때마다 로그인하기 전에 사용자 ID가 동적으로 변경되는 향상된 인증 프로토콜을 제안하였다. 본 논문에서는 Andola 등이 제안한 프로토콜의 동작 과정 및 취약점을 분석하여, Andola 등이 제안한 프로토콜이 offline smart card attack, dos attack, lack of perfect forward secrecy, session key attack에 취약하다는 것을 밝혔다.

Many businesses and organizations use smartcard-based user authentication for remote access. In the meantime, through various studies, dynamic ID-based remote user authentication protocols for distributed multi-server environments have been proposed to protect the connection between users and servers. Among them, Qiu et al. proposed an efficient smart card-based remote user authentication system that provides mutual authentication and key agreement, user anonymity, and resistance to various types of attacks. Later, Andola et al. found various vulnerabilities in the authentication scheme proposed by Qiu et al., and overcame the flaws in their authentication scheme, and whenever the user wants to log in to the server, the user ID is dynamically changed before logging in. An improved authentication protocol is proposed. In this paper, by analyzing the operation process and vulnerabilities of the protocol proposed by Andola et al., it was revealed that the protocol proposed by Andola et al. was vulnerable to offline smart card attack, dos attack, lack of perfect forward secrecy, and session key attack.

In recent days, with the help of fast grwoing popularity of mobile devices and advances on network technology, the need for a user to share a media content on his/her multiple devices with seamless playing service. This paper shows the implementation results of a Linux streaming server for multi-device seamless play service of mulitmedia data. For this purpose, the server was designed using ffserver, a streaming server for both audio and video which supports to seek positions in the past on each live feed for multi-device seamless play service.

IP보안 카메라의 보급으로 원격에서 얼굴인식을 수행함에 있어 서버의 부하를 줄이기 위한 여러 가지 방법들이 구현되고 있다. 본 논문에서는 원격지에 있는 IP 보안 카메라 영상을 얼굴검출기능이 탑재된 DSP 보드를 통해 입력받아 얼굴검출을 수행 한 후 해당 얼굴영역 이미지를 서버로 전송하여 이를 얼굴인식 분산 처리를 통해 얼굴인식 기능을 수행한다. 결과적으로 전체적인 서버시스템 로드를 상당히 줄이는 성과와 실시간 얼굴 인식처리를 최대 256 대의 카메라를 연동하면서 수행할 수 있는 장점을 가지고 있다. 이를 수행할 수 있는 기술은 분산처리 서버기술을이용하여 한 서버 당 64채널 얼굴인식을 수행하며, 4개 분산처리 서버를 운영할 경우 250여개 카메라 채널을 통한얼굴검출 결과를 처리하는 성과를 가져올 수 있었다.

Various methods for reducing the load on the server have been implemented in performing face recognition remotely by the spread of IP security cameras. In this paper, IP surveillance cameras at remote sites are input through a DSP board equipped with face detection function, and then face detection is performed. Then, the facial region image is transmitted to the server, and the face recognition processing is performed through face recognition distributed processing . As a result, the overall server system load and significantly reduce processing and real-time face recognition has the advantage that you can perform while linked up to 256 cameras. The technology that can accomplish this is to perform 64-channel face recognition per server using distributed processing server technology and to process face search results through 250 camera channels when operating four distributed processing servers there was.

To protect the resources from unauthorized users, the remote user authentication have become an essential part in the communication network. Currently, smart card-based remote user authentication for multi-server environment is a widely used and researched method. Remote user authentication for multi-server environment has resolved the problem of users to manage the different identities and passwords. Recently, Mishra et al. proposed a multi-server authenticated key agreement scheme using smart cards, where they claim that their scheme is secure enough and could resist the various well known attacks. However, in this paper, we have shown that their scheme is not secure as they have claimed and can suffer from impersonation attacks and stolen smart card attack. Later in the paper, we propose an improved multi-server authentication scheme using smart cards, which not only overcomes the mentioned weaknesses but also can provide more functionality features.

Authentication and key agreement protocol becomes an important security issue for multi-server architecture. Combining biometrics with password enhances the level of security. Recently, Baruah et al. analyzed that Mishra et al.’s protocol has several drawbacks and proposed an improved biometric based multi-server authentication scheme. They claimed that their scheme satisfies all the required security attributes for a secure authentication. In this paper, we indicate that their scheme is not secure against key reveal attack, replay attack, and smart card forgery attack. Any registered user can retrieve the session key or launch the replay attack by eavesdropping on the communication channel. In addition, registered user can forge smart card when colluding with registered server.

Remote user authentication scheme with key agreement is a very practical mechanism to verify a remote user and then provide secure communication. Furthermore, many network environments have been becoming multi-server based due to the rapid growth of computer networks. Therefore, more and more researches have been focused on proposing smart card based remote authentication scheme with session key agreement for multi-server environment. Recently, Tsaur, Li and Lee (2012) proposed such a novel scheme which adopts a self-verified timestamp technique to help the smart card based authentication scheme not only effectively achieve password-authenticated key agreement but also avoid the difficulty of implementing clock synchronization in multi-server environments. They claimed that their scheme is against various attacks and more efficient. However, we observe that Tsaur-Li-Lee's scheme is still vulnerable to off-line password guessing attack, insider attack and malicious user attack. Besides, Tsaur-Li-Lee's scheme has no password change phase and also suffers from weaknesses of static identity and inefficiency in wrong password detection. In this paper, we propose an improved dynamic identity based scheme to eliminate all the security and efficiency weaknesses without decreasing other security performances.

Recently, more and more researches have been focused on proposing dynamic identity based remote authentication scheme for multi-server environment. In 2011, Lee, Lin and Chang proposed an improved scheme to remedy the weaknesses of Hsiang-Shih's scheme. However, we observe that Lee-Lin-Chang's scheme is still vulnerable to stolen smart card attack and malicious server attack. Besides, the password change phase of Lee-Lin-Chang's scheme is neither efficient enough nor convenient to users. In this paper, we propose an improved scheme to remove the aforementioned weaknesses and simultaneously not to decrease other security features. In the proposed scheme, there is no useful information can be obtained from the values stored in smart cards. Thus the stolen smart card attack can be blocked. To avoid malicious server attack, we move the user authentication process from service providing servers to the registration center, which can ensure each server has a different secret key. Through comparing with several schemes proposed recently, we demonstrate our proposed scheme is more secure and efficient. Therefore, the proposed scheme is more practicable.

Remote user authentication schemes provide a system to verify the legitimacy of remote users’ login request over insecure communication channel. Since last few years many authentication schemes have been proposed including several new features and ideas. But, due to the advancement of computational process they are suffering from various possible attacks. This is the reason because of which attaining the security becomes a prime issue and major challenge among the researchers. In this paper, we have proposed a new user friendly authentication scheme that can provide the higher security at lower computational cost. This scheme provides extra level of security by adopting the user-defined image for password generation. Finally, the security analysis and performance evaluation are made to proof the efficiency of our scheme.

Generally, if a user wants to use numerous different network services, he/she must register himself/herself to every service providing server. It is not easy task for users to remember these different identities and passwords for each server. To solve the problem, various multi-server authentication schemes have been proposed. Recently, Wang et al. proposed a smartcard based multi-server authentication scheme. They claimed that their scheme is secure against impersonation attack, server spoofing attack and offline dictionary attack, and provides forward secrecy. However, through careful analysis, we find that Wang et al.’s scheme is still vulnerable to password guessing attack with stolen smartcard. Furthermore, we propose an enhanced smartcard based multi-server authentication scheme to cope with the security problem in Wang et al.’s scheme. The proposed scheme is suitable for use in distributed multi-server architecture since it provides mutual authentication, efficiency and security.

Recently, Chang and Cheng proposed a robust mechanism for smart card based remote logins in a multi-server architecture. However, based on the security analyzes conducted by us, we find their mechanism is vulnerable against smart card lost problems, leak-of-verifier attack and session key disclosure attack. To eliminate all identified security threats in their mechanism, we further proposed an improved version of two-factor based user authentication protocol in multi-server networks.

As computer networks become an essential part of our daily life, therefore, protecting the resources from unauthorized users come forward with more challenging and complicated task for the researchers. From the last few decades, many number of password-based authentication schemes have been adopted in multi-server environment to protect the resources from any adversary means. Recently, Li et al. has proposed a dynamic-id based remote user authentication scheme and claimed that their scheme can provide more security than existing schemes and is suitable for practical applications. But, in this paper, we have shown that their scheme is not too much secured as they have claimed and it can suffer from stolen smart card attack, user impersonate attack and lack of some important features of smart card as well. To overcome these security flaws, we have further proposed an improved anonymous authentication scheme.

Multi-server authentication schemes are very practical from a user point of view, since they allow a user to get access to different services on different servers with one single registration. Smart card based approaches lead to more secure systems because they offer two-factor authentication, based on the strict combination of user's password and the possession of the smart card. In this paper, we first show that a previously proposed scheme does not satisfy perfect forward secrecy and is not resistant against insider attacks. Next, we propose a very efficient smart card based authentication scheme, solely using xor and hash operations, which is resistant against dishonest users and servers. Also anonymity and untraceability of user's behaviour is avoided.

Authentication is an important and basic security service for many network based applications, which allows the registered user access remote services after the validity of his/her identity is verified by the remote server. Password, smart card and biometric are three frequently used factors in authentication, and some remote user authentication schemes for different environments had been presented based on these factors by researchers. Recently, Baruah et al. pointed out the weaknesses of Mishra et al.’s three factors user authentication scheme for multi-server environments, and they proposed an enhanced scheme. They claimed that their scheme has many security features and can resist some common attacks. However, based on our analysis, Baruah et al.’s scheme cannot resist stolen smart card attack, cannot protect user’s anonymity, and it is also vulnerable to Denial of Service attack. In this paper, an enhanced three factors user authentication scheme for multi-server environments based on fuzzy extractor technology is proposed, and the analysis show that the proposed scheme is more security and efficient than other related schemes.

Multi-server environments are that the user registers the single registration server and since the user uses the service to authenticate on multi-server. For this, many user authentication schemes have been proposed for multi-server environments. In 2013, Li, et al., proposed dynamic ID based remote user authentication scheme for multi-server environments. Unfortunately, their scheme is vulnerable to forgery attacks and replay attacks. In this paper, we analyze the security vulnerabilities of Li et al.’s scheme, and propose dynamic ID based remote user authentication scheme for multi-server environments. The proposed scheme ensures the safety to various attacks such as forgery attacks and replay attacks. Just like the existing schemes, our scheme is efficient at using the hash function and exclusive-OR operation.

Secure user authentication without repeating registration is one of the important issues in multi-server networks that needs to be adequately addressed. Recently, two-factor (smart card and password) based remote user authentication protocols have been widely introduced due to their low constructional cost and convenient usability for the authentication purpose. In 2011, Chang and Cheng proposed a smart card and password based remote login mechanism for multi-server environments. However, in this paper, we found that Chang-Cheng's mechanism suffers from susceptibility to security attacks. As a result, we introduced an improved version of smart card based password authentication mechanism in multi-server networks. Compared with other related protocols, performance analysis shows that our proposed mechanism is still cost-efficient for the real application in multi-server environments.

Recently, Lee et al. proposed a secure dynamic ID based remote user authentication scheme for multi-server environment. They claimed their scheme can remedy the weaknesses of prior schemes and is thus more effective. However, we find Lee et al.'s scheme still fails to achieve the anonymity and has the security weakness of a smart card clone. In this article, we shall propose a new scheme to improve Lee et al.’s scheme. Our scheme not only overcomes the weaknesses of Lee et al.'s scheme, but also maintains a high efficiency standard.