• The KIPS Transactions:PartC
• /
• v.14C no.6
• /
• pp.463-470
• /
• 2007

Revocation is one of the main difficulties faced in implementing Public Key Infrastructures(PHs). Boneh, Ding and Tsudik first introduced a mediated cryptography for obtaining immediate revocation of RSA keys used in PKIs. Their method is based on the idea that each user's private key can be split into two random shares, one of which is given to the user and the other to an online security mediator(SEM). Thus any signature or decryption must be performed as a cooperation between a user and his/her associated SEM and revocation is achieved by instructing the mediator SEM to stop cooperating the user. Recently, Libert and Quisquater showed that the fast revocation method using a SEcurity Mediator(SEM) in a mRSA can be applied to the Boneh-Franklin identify based encryption and GDH signature schemes. In this paper we propose a mediated identity based signature(mIBS) with batch verification which apply the SEM architecture to an identity based signature. Libert's GDH siganture scheme is not forward secure even though forward security is an important and desirable feature for signature schemes. We propose an efficient key udating mediated signature scheme, mKUS based on mIBS and analyze its security and efficiency.

• Journal of Internet Technology
• /
• v.22 no.5
• /
• pp.1069-1082
• /
• 2021

The Internet of Things (IoT) is vulnerable to a wide range of security risks, which can be effectively mitigated by applying Cyber Threat Intelligence (CTI) sharing as a proactive mitigation approach. In realizing CTI sharing, it is of paramount importance to guarantee end-to-end protection of the shared information as unauthorized disclosure of CTI is disastrous for organizations using IoT. Furthermore, resource-constrained devices should be supported through lightweight operations. Unfortunately, the aforementioned are not satisfied by the Hypertext Transfer Protocol Secure (HTTPS), which state-of-the-art CTI sharing systems mainly depends on. As a promising alternative to HTTPS, Ephemeral Diffie-Hellman over COSE (EDHOC) can be considered because it meets the above requirements. However, EDHOC in its current version contains several security flaws, most notably due to the unprotected initial message. Consequently, we propose a lightweight end-to-end privacy-preserving security protocol that improves the existing draft EDHOC protocol by utilizing previously shared keys and keying materials while providing ticket-based optimized reauthentication. The proposed protocol is not only formally validated through BAN-logic and AVISPA, but also proved to fulfill essential security properties such as mutual authentication, secure key exchange, perfect forward secrecy, anonymity, confidentiality, and integrity. Also, comparing the protocol's performance to that of the EDHOC protocol reveals a substantial improvement with a single roundtrip to allow frequent CTI sharing.

• Journal of KIISE:Information Networking
• /
• v.30 no.4
• /
• pp.484-493
• /
• 2003

Proxy signature scheme is a cryptographic protocol that an original signer delegates her signing capability to a proxy signer, and then the proxy signer is able to create signatures on behalf of the original signer. In general, there is time-limit for which the signing capability of the proxy signer is valid. One of methods to limit the valid delegation time is to make public delegation information contain the expiration date of the delegation. however, in this method we cannot prevent the proxy signer from signing after the valid delegation is expired because no one knows the exact time when the proxy signer signed a message. The validity of the past legal signatures cannot be preserved in case that the proxy singer´s key is compromised during the delegation period. In this paper, we propose a new scheme, time-limited forward-secure proxy signature protocol, which prevents the proxy singer from signing after the valid delegation is expired and which preserves the validity of the past legal signatures even if the signing key is compromised. The proposed scheme does not require the exact time-information by making an original signer control time-related parameters and satisfies the forward-security property in each update-period of the proxy signing key. The time-period is determined according to the application characteristics or security policies.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.05a
• /
• pp.295-297
• /
• 2008

Session Initiation Protocol (SIP) has become the call control protocol of choice for Voice over IP (VoIP) networks because of its open and extensible nature. However, the integrity of call signaling between sites is of utmost importance, and SIP is vulnerable to attackers when left unprotected. Currently a hop-by-hop security model is prevalent, wherein intermediaries forward a request towards the destination user agent server (UAS) without a user agent client (UAC) knowing whether or not the intermediary behaved in a trusted manner. This paper presents an integrated security model for SIP-based VoIP network by combining hop-by-hop security and end-to-end security.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.10a
• /
• pp.86-87
• /
• 2014

Although the importance of information security industry has been growing these days, the research of industrial respect for the industry has been rarely performed. This paper provides one definition of the information security industry and the industry classification system according to the definition. The purpose of this study is to provide the basic data for the industry development strategy by analyzing economic ripple effect on the domestic information security industry.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2002.11a
• /
• pp.64-67
• /
• 2002

본 논문에서는 이동통신용 인증 및 키 교환 프로토콜을 분석하였다. Forward secrecy나 signcryption 성질을 만족하기 위해서 프로토콜의 변형이 필요하였고 이 때문에 원래의 보안요구사항이 훼손되지도 않았다. 또한, 클라이언트의 연산능력을 고려한 최근에 제안된 프로토콜에 관해서도 연구하여 연산량과 통신 오버헤드 관점에서 기존의 프로토콜보다 우수함이 분석되었다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2003.12a
• /
• pp.428-433
• /
• 2003

공개키 기반 구조에서 개인키의 노출은 심각한 문제를 일으킬 수 있다. 현재의 전자서명 기법에서는 서명자가 자신의 개인키 도난에 대한 사실을 인지하지 못하면, 공격자는 원하는 만큼의 전자서명을 생성 할 수 있다. 따라서 서명자가 개인키를 노출하였을 때 서명자를 보호 할 수 있는 전자서명 기법이 필요하다. 본 논문에서는 Pairing을 이용한 키 전개방식 전방보안 전자서명기법을 제시하고, 이를 Schnorr 서명기법에 적용한다. 제안하는 서명기법은 기존의 전자서명기법과 호환됨으로써 매우 실용적이다.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.5 no.2
• /
• pp.123-131
• /
• 2009

Process Control Systems (PCSs) or Supervisory Control and Data Acquisition (SCADA) systems have recently been added to the already wide collection of wireless sensor networks applications. The PCS/SCADA environment is somewhat more amenable to the use of heavy cryptographic mechanisms such as public key cryptography than other sensor application environments. The sensor nodes in the environment, however, are still open to devastating attacks such as node capture, which makes designing a secure key management challenging. Recently, Nilsson et al. proposed a key management scheme for PCS/SCADA, which was claimed to provide forward and backward secrecies. In this paper, we define four different types of adversaries or attackers in wireless sensor network environments in order to facilitate the evaluation of protocol strength. We then analyze Nilsson et al. 's protocol and show that it does not provide forward and backward secrecies against any type of adversary model.

• ETRI Journal
• /
• v.39 no.5
• /
• pp.729-736
• /
• 2017

This work investigates secure cluster-aided multi-hop randomize-and-forward networks. We present a hop-by-hop multi-hop transmission scheme with relay selection, which evaluates for each cluster the relays that can securely receive the message. We propose an analytical model to derive the secure connectivity probability (SCP) of the hop-by-hop transmission scheme. For comparison, we also analyze SCPs of traditional end-to-end transmission schemes with two relay-selection policies. We perform simulations, and our analytical results verify that the proposed hop-by-hop scheme is superior to end-to-end schemes, especially with a large number of hops or high eavesdropper channel quality. Numerical results also show that the proposed hop-by-hop scheme achieves near-optimal performance in terms of the SCP.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.1
• /
• pp.344-365
• /
• 2020

Providing security has been always on priority in all areas of computing and communication, and for the systems that are low on computing power, implementing appropriate and efficient security mechanism has been a continuous challenge for the researchers. Radio Frequency Identification (RFID) system is such an environment, which requires the design and implementation of efficient security mechanism. Earlier, the security protocols for RFID based on hash functions and symmetric key cryptography have been proposed. But, due to high strength and requirement of less key size in elliptic curve cryptography, the focus of researchers has been on designing efficient security protocol for RFID based on elliptic curves. In this paper, an efficient elliptic curve signcryption based security protocol for RFID has been proposed, which provides mutual authentication, confidentiality, non-repudiation, integrity, availability, forward security, anonymity, and scalability. Moreover, the proposed protocol successfully provides resistance from replay attack, impersonation attack, location tracking attack, de-synchronization attack, denial of service attack, man-in-the-middle attack, cloning attack, and key-compromise attack. Results have revealed that the proposed protocol is efficient than the other related protocols as it takes less computational time and storage cost, especially for the tag, making it ideal to be used for RFID systems.