• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.1
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• pp.115-129
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• 2010

As the fixed mobile communication tools using the internet are developed, the off-line services are serviced through on-line on the internet. our society is divided into the real world and the cyber world. In the cyber world, the authentication to the user is absolutely required. The authentication is divided into the real-name authentication and the anonymous authentication by the kind of the internet service provider. There are some ISPs needed the real-name authentication and there are others ISPs needed the anonymity authentication. The research about the anonymity authentication is steadily established to these days. In this paper, we analyze the problem about blind signature, group signature, ring signature, and traceable signature. And we propose a method of anonymity authentication using the public certificate. In the proposal, the anonymity certificate have the new structure and management. Certificate Authority issues several anonymity certificates to a user through the real-name authentication. Several anonymity certificates give non-linked and non-traceability to the attacker.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.2
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• pp.139-149
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• 2023

CBDC has characteristics similar to e-payments in which all records are kept by logs, so it is difficult to satisfy the anonymity level of cash. Therefore, in this study, the CBDC model that encrypts all transaction contents using the Diffie-Hellman key sharing algorithm was presented to enhance anonymity. The proposed model provides unlinkability anduntraceability. In addition, a CBDC certificate that uses pseudonym is used. Through this certificate, illegal transactions that require tracking can be tracked later by authorized institutions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1546-1565
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• 2019

Signcryption schemes offer the possibility to simultaneously sign and encrypt a message. In order to guarantee the authentication of both signer and receiver in the most efficient way during the signcryption, certificate based solutions have been proposed in literature. We first compare into detail three recently proposed certificate based signcryption systems relying on the elliptic curve discrete logarithm problem and without the usage of compute intensive pairing operations. Next, we demonstrate how the performance of these certificate based systems can be improved by using the Elliptic Curve Qu Vanstone (ECQV) implicit certificates. What is more, generalized signcryption schemes are easily derived from these schemes and the anonymity feature of sender and receiver is already inherently included or can be very efficiently obtained without a significant additional cost.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.753-773
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• 2019

CV(Connected Vehicle) technology provides safety-related services and user convenience-related services to vehicle. Safety-related services can cause privacy problem by continuously transmitting vehicle information to nearby vehicles or base stations. Therefore, safety-related services should provide vehicle anonymity for privacy protection. However, if convenience-related services such as payment services fail to provide vehicle anonymity, driver information related to safety-related services may also be leaked. In this paper, we design a payment protocol based on ECQV(Elliptic Curve Qu-Vanstone) impicit certificate and group signature that provides BU-anonymity and traceability. The proposed payment protocol makes it impossible to track vehicles from payment transactions history by separating roles of payment system components. Moreover, we define the security requirements that the vehicle payment protocol must satisfy and show that the protocol satisfies the requirements.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2921-2929
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• 1998

We propose an efficient off-line electronic cash system based on the certificate issued by Certificate Authority. It satisfies all the basic requirements for electronic payment system such as cash unforgeability, cash anonymity, double spending detection, no framing, etc. Our proposed system is very computationally efficient in the sense that: (1) the number of exponentiation operation imposed on the user during withdrawal phase is much smaller than any existing off-line electronic cash schemes, (2) all the computation of user's during withdrawal phase can be performed by off-line pre-processing. So the proposed system is suitable to be implemented by smart cards in both memory and computation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.5
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• pp.59-66
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• 2006

A Certification Authority issues X.509 public key certificates to bind a public key to a subject. The subject is specified through one or more subject names in the 'subject' or 'subjectAltName' fields of a certificate. In reality, however, there are individuals that have the same or similar names. This ambiguity can be resolved by including a 'permanent identifier' in all certificates issued to the same subject, which is unique across multiple CAs. But, a person's unique identifier is regarded as a sensitive personal data. Such an identifier cannot simply be included as part of the subject field, since its disclosure may lead to misuse. We present a new method for secure and accurate user authentication through the PEPSI included in the standard certificate extension of a X.509 certificate. The PEPSI can be served not only for user authentication but also for the user anonymity without divulging personal information.

• The KIPS Transactions:PartD
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• v.12D no.3 s.99
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• pp.499-506
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• 2005

A hash chain is a structure organized by hash function with high speed in computation. Systems using the hash chain are using extensively in various cryptography applications such as one-time passwords, server-supported signatures and micropayments. However, the most hash chain based on the system using pre-paid method provides anonymity but has the problem to increase payment cost. In this paper, we propose a new hash chain based on the micropayment system to keep user anonymity safe through blind signature in the withdrawal process of the root value without disclosing privacy information, and to improve efficiency by using secret key instead of public key in the system without the role of certificate.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.201-206
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• 2007

Development of Information and Communication technology coming to activity of internet banking and electronic business, and smart card of medium is generalized prevailing for user authentication of electronic signature certificate management center with cyber cash, traffic card, exit and entrance card. In field that using public network, security of smart cart and privacy of card possessor's is very important. Point of smart card security is use safety for smart card by user authentication. Anonymous establishment for privacy protection and denial of service attack for availability is need to provision. In this paper, after analyze for Hwang-Li, Sun's, L-H-Y scheme, password identify element is a change of safety using one time password hash function. We proposed an efficient new smart card authentication protocol against anonymity and denial of service.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.189-199
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• 2005

Now it is increasing the necessity for micropayment system according to activation for trade on internet. Because of the reason, it is requesting safety for personal information as well as for payment cost. But current micropayment systems cannot support anonymity or have heavy overheads in payment process. This paper suggests a micropayment system to keep anonymity of users and also to keep payment cost safe. The proposed system is to use blind signature anonymous ID which is combined nonce with an encryption of personal information. It also keeps payment cost of users by reconfirmation payment cost and product from certification and increases the computational efficiency by using secret key and session key instead of public key.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.4 s.304
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• pp.25-32
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• 2005

The spread of mobile devices, PDAs and sensors has enabled the construction of ubiquitous computing environments, transforming regular physical spaces into 'Smart space' augmented with intelligence and enhanced with services. However, the deployment of this computing paradigm in real-life is disturbed by poor security, particularly, the lack of proper authentication and authorization techniques. Also, it is very important not only to find security measures but also to preserve user privacy in ubiquitous computing environments. In this Paper, we propose efficient user authentication and authorization model with anonymity for the privacy-preserving for ubiquitous computing environments. Our model is suitable for distributed environments with the computational constrained devices by using MAC-based anonymous certificate and security association token instead of using Public key encryption technique. And our Proposed Protocol is better than Kerberos system in sense of cryptographic computation processing.