Yalin Chen , Jue-Sam Chou , Fang-Qi Zhou ,Shu-Mei Hsu Institute of information systems and applications, National Tsing Hua University Yalin78900@gmail.com Department of Information Management, Nanhua University, Taiwan *: corresponding author: jschou@nhu.edu.tw Tel: 886+ (05)+272-1001 ext.56536 Department of Information Management, Nanhua University, Taiwan zz66016@gmail.com 4 Department of Mathematics and Physics Education, Chiayi University, Taiwan m8503015@gmail.com

Recently, Kumari et al., pointed out that Chang et al.’s scheme “Untraceable dynamic-identity-based remote user authentication scheme with verifiable password update” has several drawbacks and does not provide any session key agreement. Hence, they proposed an improved remote user authentication scheme with key agreement based on Chang et al.’s protocol. They claimed that the improved method is secure. However, we found that their improvement still has both anonymity breach and smart card loss password guessing attack which cannot be violated in the ten basic requirements advocated for a secure identity authentication using smart card by Liao et al. Thus, we modify their protocol to encompass these security functionalities which are needed in a user authentication system using smart card.

Nowadays, with such a huge amount of information available online, one key challenge is how to retrieve target data efficiently. A recent state-of-art solution, k-means hashing (KMH), codes data via a string of binary code obtained by iterative k-means clustering and binary code optimizing. To deal with high dimensional data, KMH divides the space into low-dimensional subspaces, places a hypercube in each subspace and finds its proper location by the mentioned optimizing process. However, the complexity of the optimization increases rapidly when the dimension of the hypercube increases. To address this issue, we propose an improved hashing method stacked k-means hashing (SKMH). The main idea is to increase the approximation by a coarse-to-fine multi-layer lower-dimensional cubes. With these kinds of lower-dimensional cubes, SKMH can achieve a similar approximation ability via a less optimizing time, compared with KMH method using higher-dimensional cubes. Extensive experiments have been conducted on two public databases, demonstrating the performance of our method by some common metrics in fast nearest neighbor search.

Recently, Kumari et al. pointed out that Chang et al.’s scheme “Untraceable dynamic-identity-based remote user authentication scheme with verifiable password update” not only has several drawbacks, but also does not provide any session key agreement. Hence, they proposed an improved remote user authentication Scheme with key agreement on Chang et al.’s Scheme. After cryptanalysis, they confirm the security properties of the improved scheme. However, we determine that the scheme suffers from both anonymity breach and he smart card loss password guessing attack, which are in the ten basic requirements in a secure identity authentication using smart card, assisted by Liao et al. Therefore, we modify the method to include the desired security functionality, which is significantly important in a user authentication system using smart card.

Recently, Farasha et al. proposed an efficient user authentication and key agreement scheme for heterogeneous wireless sensor network tailored for the Internet of Things environment. By using BAN-logic and AVISPA tools, they confirm the security properties of the proposed scheme. However, after analyzing, we determine that the scheme could not resist the smart card loss password guessing attack, which is one of the ten basic requirements in a secure identity authentication using smart card, assisted by Liao et al. Therefore, we modify the method to include the desired security functionality, which is significantly important in a user authentication system using smart card.

Recently, Fan et al. proposed a novel e-cash scheme which allows a user to recover the e-cash he lost. They claimed their e-cash possesses properties of anonymity, unlinkability (i.e. untraceability), bank-off-line payment, doublespending detection, and anonymity revocation. The ecash untraceability is greatly related to users’ privacy and indicates that no one including the issuer bank can link e-cash to any user when the e-cash is legally spent. Although, the authors have formally proved the unlinkability of their scheme, we still found a loophole to compromise user’s privacy. That is, an issuer bank or an attacker who intrudes the issuer bank’s system can link e-cash to a user by collecting e-cash withdrawal and deposit transaction messages. This may make the user’s shopping behaviors or location information exposed.

Recently, Fan et al. proposed a novel e-cash scheme which allows a user to recover the e-cash he lost. They claimed their e-cash possesses properties of anonymity, unlinkability (i.e. untraceability), bank-off-line payment, doublespending detection, and anonymity revocation. The ecash untraceability is greatly related to users’ privacy and indicates that no one including the issuer bank can link e-cash to any user when the e-cash is legally spent. Although, the authors have formally proved the unlinkability of their scheme, we still found a loophole to compromise user’s privacy. That is, an issuer bank or an attacker who intrudes the issuer bank’s system can link e-cash to a user by collecting e-cash withdrawal and deposit transaction messages. This may make the user’s shopping behaviors or location information exposed.

Radio frequency identification tag authentication protocols are generally classified as non-full-fledged and full-fledged, according to the resource usage of the tags. The non-full-fledged protocols typically suffer de-synchronization, impersonation and tracking attacks, and usually lack scalability. The full-fledged protocols, supporting cryptographic functions, are designed to overcome these weaknesses. This paper examines several elliptic-curve-cryptography (ECC)-based full-fledged protocols. We found that some still have security and privacy issues, and others generate excessive communication costs between the tag and the back-end server. Motivated by these observations, we construct two novel protocols, PI and PII. PI is designed for secure environments and is suitable for applications, including E-Passport and toll payment in vehicular ad-hoc networks. PII is for hostile environments and can be applied in pseudonymous payment and anti-counterfeiting services. After analysis, we conclude that PII can resist many attacks, outperform previous ECC-based proposals in communication efficiency, and provide mutual authentication function and scalability.

Secure electronic payment instruments play an important role in retail electronic commerce. As in most countries, people in Taiwan often use credit cards for payments on Internet shopping. However, the information contained in the card includes sensitive data like card number, valid date, and CVC (Card Verification Code) which all easily suffer data leakage, or impersonation attacks. This may cause the banks, merchants, or user to suffer serious losses. In this paper, we propose an IDbased untraceable electronic cash without card number or personal information to mitigate the risk of data leakage. Meanwhile, our method also considers preventing the anonymity abuse and adds the function of anonymity revocation through a trust party. In addition, due to the proposed is an IDbased scheme, it has the advantage of PKI (Public Key Infrastructure) free and thus save the certificate management cost.

Recently, Worku et al. pointed out that the work “privacy-preserving public auditing for data storage security in cloud computing” proposed by Wang et al. is insecure and their second work “privacypreserving public auditing for secure cloud the storage” is inefficient. Thus, they offered a secure and efficient-privacy public auditing scheme for cloud storage. They claimed that their system is provably secure in the random oracle model and the operation is effective. However, after crypto-analysis, we found that the scheme cannot reach the security goal, it has the existential forgery attack. We, therefore, alter it to incorporate the desired privacy preserving requirement, which is very significant in a privacy-preserving public auditing protocol for cloud storage.

Recently, Shm et al. Proposed an efficient identity-based broadcast authentication scheme based on Tso et al.’s IBS scheme with message recovery to achieve security requirements in wireless sensor networks. They claim that their scheme can achieve security requirements and mitigated DOS attack by limiting the times of signature verification failures in wireless sensor networks (WSN). However, we found that the scheme cannot attain the security level as they claimed. We will demonstrate it in this article.

Recently, Baseri et al. proposed a secure untraceable off-line electronic cash system. They claimed that their scheme could achieve security requirements of an e-cash system such as, untraceability, anonymity, unlinkability, double spending checking, un-forgeability, date-attachability, and prevent forging coins. They further prove the un-forgeability security feature by using the hardness of discrete logarithm problems. However, after cryptanalysis, we found that the scheme cannot attain the security feature, untraceability. We, therefore, modify it to comprise this desired requirement, which is very important in an e-cash system.

1 Department of Information Management, Nanhua University Chiayi 622 Taiwan, *: corresponding author jschou@mail.nhu.edu.tw 2,3 Department of Information Management, Nanhua University Chiayi 622 Taiwan, 2 g6451519@mail1.nhu.edu.tw 3 g0069020@mail1.nhu.edu.tw Tel: 886+ (0)5+272-1001 ext.56536 4 Institute of information systems and applications, National Tsing Hua University d949702@oz.nthu.edu.tw ______________________________________________________________________ Abstract Recently, Khan et al. proposed an enhancement on a remote authentication scheme designed by Wang et al. which emphasizes on using dynamic identity. They claim that their improvement can avoid insider attack. However, we found the scheme lacks the anonymity property. Moreover, R. Madhusudhan et al. indicate their scheme also suffers the insider attack. Due to these observations, in this paper we propose a novel one which not only anonymously authenticates the remote user by using only two passes but also satisfies the ten requirements of an authentication scheme using smart card mentioned by Liao et al..

Recently, Tsai et al., Liao et al. and Li et al. each proposed a multi-server authentication protocol. They claimed their protocols are secure and can withstand various attacks. However, we found some security loopholes in each of their schemes, for example, both Tsai et al.’s and Liao et al.‘s schemes suffers from server spoofing attack by an insider server. Li et al.s’ suffers from the lost smart card password-guessing attack. In addition, Liao et al.‘s scheme also has the off-line password-guessing attack. In this paper, we will first review then show the attacks on each of the schemes. Then, based on Li et al.’s scheme, we proposed a novel one and examined its security in several security features. After security analysis, we concluded that our protocol outperformed Li et al.’s scheme in the security feature of lost smart card password-guessing attack.

Recently, researchers have proposed many non-interactive deniable authentication (NIDA) protocols. Most of them claim that their protocols possess full deniability. However, after reviewing, we found that they either cannot achieve full deniability, or suffer KCI or SKCI attack; moreover, lack efficiency, because they are mainly based on DLP, factoring problem, or bilinear pairings. Due to this observation, and that ECC provides the security equivalence to RSA and DSA by using much smaller key size, we used Fiat-Shamir heuristic to propose a novel ECC-based NIDA protocol for achieving full deniability as well as getting more efficient than the previous schemes. After security analyses and efficiency comparisons, we confirmed the success of the usage. Therefore, the proposed scheme was more suitable to be implemented in low power mobile devices than the others. Keyword: deniable authentication protocol, Fiat-Shamir heuristic, perfect zero-knowledge, key compromise impersonation attack, voting systems

Recently, researchers have proposed several nice multi-server authentication protocols. They claim that their protocols are secure and can withstand various attacks. However, after reviewing their schemes, we found that they although are perfect whereas flawed. Due to this observation, in this paper, we list the weakness found in these recent literatures.

We provide a brief rebuttal of Chang (2012), who suggested that there were flaws in our article, Chen et al. (2011), that deserved further investigation and comment. We believe that these criticisms are unfounded, and offer some additional details related to the intractable discrete elliptic curve discrete logarithm problem to further support the case we wish to make.

ABSTRACT In a multi‐server environment, a user only needs to register at the registration center once instead of repeatedly registering in each server. After registration, the user can access the resources of any of the servers in the system. Many protocols have been proposed for the same. Recently, Geng–Zhang, Zhu et al ., and Yoon–Yoo each proposed a multi‐server authentication scheme. They claimed that their schemes are secure and can withstand various attacks. However, after analyses, we found that their schemes are deficient. In this paper, we first demonstrate the deficiencies of these three protocols in turn and then show our improvement on Geng–Zhang's protocol. Our improvement makes use of both the user's and the server's secrecy to achieve mutual authentication. This results in a two‐pass multi‐server authentication scheme. We have analyzed its security with respect to several factors such as mutual authentication, perfect forward and backward secrecy, and prevention of smart‐card‐lost attack. Moreover, almost all of the parameters required for a user to log on to a server can be pre‐computed. This is very important for a low‐energy mobile computing device. That is, our improvement is not only one of the most efficient and secure schemes in this area but also suitable for mobile device. Copyright © 2011 John Wiley & Sons, Ltd.

Recently, many researchers have proposed RFID authentication protocols. These protocols are mainly consists of two types: symmetric key based and asymmetric key based. The symmetric key based systems usually have some weaknesses such as suffering brute force, de-synchronization, impersonation, and tracing attacks. In addition, the asymmetric key based systems usually suffer from impersonation, man-in-the-middle, physical, and tracing attacks. To get rid of those weaknesses and reduce the system workload, we adopt elliptic curve cryptosystem (ECC) to construct an asymmetric key based RFID authentication system. Our scheme needs only two passes and can resist various kinds of attacks. It not only outperforms the other RFID schemes having the same security level but also is the most efficient.