• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.7 no.2
• /
• pp.11-18
• /
• 1997

Chaum and Heyst first proposed group signature which is based on the undeniable signature. So, a receiver of the signature can't verify a group signature without cooperation of the signer and, in case of dispute later on, he can't reveal the identity of the signer without help of the group members. Park et. al. proposed an id-based group signature with self-authentication, in which the receiver of the signature reveals the identity of the signer without help of the group members. However, the proposed scheme has two problem : 1) the receiver can't identify the signer, since every keys of the group members hold the identification procedure. 2) By collusion of the group members, new secret key for a group signature can be computed and the secret key of the trusted center can be revealed.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.7 no.2
• /
• pp.19-26
• /
• 1997

In this paper, we propose an RSA multisignature scheme with no bit expansion in which the signing order is not restricted. In this scheme we use RSA moduli with the same bit length. the most 1 bits of which are same. The proposed scheme is based on these RSA moduli and a repeated exponentiation of Levine and Brawley. Kiesler and Harn first utilize the repeated exponentiation technique in their multisignature scheme, which requires 1.5m exponentiations for signing, where m is the number of signers. However, the proposed scheme requires (equation omitted) m exponentiation. So if l is sufficiently large (l $\geq$ 32), then we can neglect the vaue (equation omitted

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.10 no.4
• /
• pp.47-57
• /
• 2000

This paper proposes efficient anonymous fingerprinting with improved automatic identification of redistributors in electronic commerce of digital contents. The proposed scheme by Domingos in Eletronic Letters is inefficient in electronic commerce, because of pass numbers in registration protocol and exponential computations in identification protocol. Our scheme is reduced 2-pass in registraton protocol and is required only 1 time exponential computation than his in identification protocol. According to electronic commerce of digital contents used in ordinary life, our schemes values are increased.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.11 no.5
• /
• pp.97-104
• /
• 2001

In this paper, we propose Recoverable Password Based Key Exchange Protocol(RPKEP). RPKEP has user who has password, server which share the secret key information with user, and password recovery agency(PRA) which help to recover the user\`s password. Proposed protocol has some advantages that it is secure against off-line dictionary attack which is considered most important in password based key exchange protocol and suer\`s security is preserved even though user\`s secret information stored in the server is disclosed. By applying Chaum\`s blind signature scheme in the process of password recovery, even the PRA can\`t obtain any information about user\`s password.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.12 no.3
• /
• pp.61-76
• /
• 2002

To ensure PKI systems' reliability, the security for PKI systems evaluation is required. But, unfortunately, the systematic security evaluation and certification of PKI systems is insufficient. In Korea, Firewall and intrusion detection system's security evaluation and certification has been enforced, but research of PKI systems’ evaluation is insufficient. This paper provides a PKI system evaluation criteria. This paper specifies a 7 level of the functional and assurance security requirements for a PKI system. And this PKI system evaluation criteria provides a compatibility with CC(Common Criteria) and KISES(Korea Information Security Evaluation Systems).

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.12 no.1
• /
• pp.11-20
• /
• 2002

In 1998, A. Young and M. Yung proposed the auto-recovery auto-certificate cryptosystem in public key infrastructure. We propose the new recoverable cryptosystem in public key infrastructure which is designed with the concept of A. Young et al's auto-recovery auto-certificate cryptosystem. It has the private/public key pairs of the user and the master private/public key pairs of the escrow authority. It is based on RSA cryptosystem and has efficiency and security.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.16 no.6
• /
• pp.151-155
• /
• 2006

In 2005, Yong and Lee proposed a buyer-seller fingerprinting protocol using symmetric and commutative encryptions. They claimed that their protocol was practical and anonymous since they used symmetric and commutative encryptions. However, an attacker can get the content embedded with one or more honest buyers' fingerprints using man-in-the-middle attack. In this letter, we point out the weakness and propose methods for improving to their protocol.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.22 no.5
• /
• pp.945-957
• /
• 2012

Electronic documents have characteristics that detecting whether an electronic document is modified or not is not an easy process. Thus verifying integrity of documents is very important for using electronic documents. To facilitate this process, various electronic document software provide digital signature capabilities on themselves. However, there were not much research on the security of digital signature function of software. Therefore, in this paper, we analyze the security of Adobe PDF, MS Word, Hancom Hangul, digital notary service and digital year-end-settlement service, and propose recommendations for implementation of digital signature funcion.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.30 no.4
• /
• pp.65-75
• /
• 2022

This study aims to forecast of Air Passenger Demand between South Korea and North Korea using the system dynamics analysis methodology that is based on the system thinking. System dynamics is not only a tool that makes the systematic thought to a model but also a computer program-based analysis methodology that mathematically models the system varying according to time variation. This study analyzed the causal relationship based on the interrelation among variables and structured them by considering various variables that affect aviation cooperation from the perspective of Air passenger demand forecasting. In addition, based on the causal relationship between variables, this study also completed the causal loop diagram that forms a feedback loop, constructed the stock-flow diagram of Inter-Korean model using Vensim program. In this study, Air passenger demand was using by the simulation variable value into System Dynamics. This study was difficult to reflect the various variables constituting the North Korea environment, and there is a limit to the occurrence of events in North Korea.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.10a
• /
• pp.383-385
• /
• 2022

Recently, as the importance of computational thinking skills has increased, several schools have opened and operated software courses for all students. Software education aims to creatively solve various problems based on coding, but it is difficult to motivate non-major learners who do not have engineering knowledge or are not interested in the IT field. Motivation for learning plays an important role in improving learners' concentration and learning efficiency. In this paper, a method of motivating non-major learners for software subjects was studied and the results were evaluated through a questionnaire.