• ETRI Journal
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• v.37 no.4
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• pp.696-706
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• 2015

This paper presents an achievable secure videoconferencing system based on quantum key encryption in which key management can be directly applied and embedded in a server/client videoconferencing model using, for example, OpenMeeting. A secure key management methodology is proposed to ensure both a trusted quantum network and a secure videoconferencing system. The proposed methodology presents architecture on how to share secret keys between key management servers and distant parties in a secure domain without transmitting any secrets over insecure channels. The advantages of the proposed secure key management methodology overcome the limitations of quantum point-to-point key sharing by simultaneously distributing keys to multiple users; thus, it makes quantum cryptography a more practical and secure solution. The time required for the encryption and decryption may cause a few seconds delay in video transmission, but this proposed method protects against adversary attacks.

• Bulletin of the Korean Mathematical Society
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• v.53 no.4
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• pp.1051-1069
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• 2016

Combining the concept of self-certified public key and message recovery, Li-Zhang-Zhu (LZZ) gives the proxy signature scheme with message recovery using self-certified public key. The security of the proposed scheme is based on the discrete logarithm problem (DLP) and one-way hash function (OWHF). Their scheme accomplishes the tasks of public key verification, proxy signature verification, and message recovery in a logically single step. In addition, their scheme satisfies all properties of strong proxy signature and does not use secure channel in the communication between the original signer and the proxy signer. In this paper, it is shown that in their signature scheme a malicious signer can cheat the system authority (SA), by obtaining a proxy signature key without the permission of the original signer. At the same time malicious original signer can also cheat the SA, he can also obtain a proxy signature key without the permission of the proxy signer. An improved signature scheme is being proposed, which involves the remedial measures to get rid of security flaws of the LZZ et al.'s. The security and performance analysis shows that the proposed signature scheme is maintaining higher level of security, with little bit of computational complexity.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.2
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• pp.205-212
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• 2003

Recently, as electronic commerce service via the Internet has expanded over the world, the standardization for the e-commerce has been strongly required. Therefore UN/CEFACT and OASIS adopted ebXML standard for the purpose of creating single global electronic marketplace. New e-Business systems should require ebXMl- based messaging system for reliable messaging delivery. In this paper, we have implemented Message Service Handler(MSH) packaging, transporting and managing e-Business messages for supporting ebXML messaging service. The MSH supports various system environments and allows high-level applications running either local or remote hosts with Remote Method Invocation(RMI) interface. In addition, MSH guarantees reliable message delivery on internet since it retransmits message in case of delivery failure and handles duplicated message and applies acknowledgement message for secure message delivery. Nowadays MSH has applied to ebXML registry/repository.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.482-494
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• 2002

In E-mail based accounting system, the remitter does not have need to find collector's account number. To transfer money to a collector's account, what remitter need is just a collector's E-mail address. But the current E-mail based accounting systems are built on SSL technology. Basically SSL provides some security services - confidentiality, user authentication and data integrity, but does not provide non-repudiation. So, in the current E-mail based accounting system, it is possible to deny transaction. And there is no receipt of transaction. In this paper, we design and implementation of a S/MIME applied Secure Payment Mechanism. In our system, every account information - account number, receiver name, amount of money, etc. - is included in a 'check' message. And this message is protected under the Secure Web-mail using S/MIME. In a view point of the convenience, users using our system do not have need to find collector's account number. And in a view point of the security, our system provides confidentiality, user authentication, data integrity and non-repudiation. Moreover our system provides a receipt.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2657-2662
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• 2010

Demand on information security in mobile devices based control system grows rapidly with a view to counteracting information hacking and leakage. Among these techniques, encryption and authentication are most common. This paper presents CBC-MAC (Cipher Block Chaining-Message Authentication Code) based mobile devices control system. The system is termed as Secure Mobile in Vehicle (SMIV)We use CBC-MAC that is one of the most efficient authentication modes to protect information against any malicious attacks. By sharing the secret key of CBC-MAC between the transmitter and receiver, it asserts authentic information. The proposed system is verified in such a way that we develop mobile devices control system, apply the CBC-MAC algorithm to the control system and validate the received data. Unlike conventional systems where the development of control mechanism in mobile devices based control systems is main concern, this proposed system offers a secure communication link of the data in mobile devices control system and therefore would be useful to the design and implementation of various mobile devices based control systems.

• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.263-274
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• 2009

Decentralized group key management mechanisms offer beneficial solutions to enhance the scalability and reliability of a secure multicast framework by confining the impact of a membership change in a local area. However, many of the previous decentralized solutions reveal the plaintext to the intermediate relaying proxies, or require the key distribution center to coordinate secure group communications between subgroups. In this study, we propose a decentralized group key management scheme that features a mechanism allowing a service provider to deliver the group key to valid members in a distributed manner using the proxy cryptography. In the proposed scheme, the key distribution center is eliminated while data confidentiality of the transmitted message is provided during the message delivery process. The proposed scheme can support a secure group communication in dynamic network environments where there is no trusted central controller for the whole network and the network topology changes frequently.

• ETRI Journal
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• v.38 no.4
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• pp.724-734
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• 2016

To achieve confidentiality, integrity, authentication, and non-repudiation simultaneously, the concept of signcryption was introduced by combining encryption and a signature in a single scheme. Certificate-based encryption schemes are designed to resolve the key escrow problem of identity-based encryption, as well as to simplify the certificate management problem in traditional public key cryptosystems. In this paper, we propose a new certificate-based signcryption scheme that has been proved to be secure against adaptive chosen ciphertext attacks and existentially unforgeable against chosen-message attacks in the random oracle model. Our scheme is not based on pairing and thus is efficient and practical. Furthermore, it allows a signcrypted message to be immediately verified by the public key of the sender. This means that verification and decryption of the signcrypted message are decoupled. To the best of our knowledge, this is the first signcryption scheme without pairing to have this feature.

• The Transactions of the Korea Information Processing Society
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• v.7 no.6
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• pp.1874-1885
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• 2000

When a receiver of ciphertext message can not decrypt a message because he has lost his private-key, the private-key of receiver and session-key of the message should be recovered. In this paper, we developed an Encapsulation based Key Recovery System (EKRS). EKRS is a new key encapsulation based key recovery system which is characterized by secretly choice of KRA, randomized target keys. n-way recovery type, and useful for commercial key recovery. EKRS is formally specified by a pictorial model, an Extended Cryptographic Timed Petri Net (ECTPN). Secure information flow and reachability of a session-key are verified by using reachability graph of ECTPN. EKRS, executing over a Public Key Infrastructure, can be used as a security solution in Web based applications such as CALS, EC an EDI.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.1144-1156
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• 2014

In Internet, IP multicast has been used successfully to provide an efficient, best-effort delivery service for group communication applications. However, applications such as multiparty private conference, distribution of stock market information, pay per view and other subscriber services may require secure multicast to protect integrity and confidentiality of the group traffic, and validate message authenticity. Providing secure multicast for group communication is problematic without a robust group key management. In this paper, we propose a group key management scheme based on the secret sharing technology to require each member by itself to generate the group key when receiving a rekeying message multicast by the group key distributor. The proposed scheme enforces mutual authentication between a member and the group key distributor while executing the rekeying process, and provides forward secrecy and backward secrecy properties, and resists replay attack, impersonating attack, group key disclosing attack and malicious insider attack.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.5
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• pp.115-124
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• 2005

We propose a new binding update(BU) protocol between mobile node(CN) and correspondent node(CN) for the purpose of preventing redirect attacks and DoS attacks observed from the existing BU protocols and enhancing the efficiency of the BU protocol. Home agent plays a role of both authentication server validating BU message and session key distribution center for MN and CN. Also propose the stateless Diffie-Hellman key agreement based on cryptographically generated address (CGA). Suity of our proposed Protocol is analyzed and compared with other protocols. The proposed protocol is more efficient than previous schemes in terms of the number of message flows and computation overhead and is secure against both redirect and DoS attacks.