• The Journal of the Korea Contents Association
• /
• v.14 no.12
• /
• pp.565-573
• /
• 2014

We have various e-commerce like on-line banking, stock trading, shopping using a PC or SmartPhone. In e-commerce, two parties use the certificate for identification and non-repudiation but, the attack on the certificate user steadily has been increasing since 2005. The most of hacking is stealing the public certificate and private key files. After hacking, the stolen public certificate and private key file is used on e-commerce to fraud. Generally, the private key file is encrypted and saved only with the user's password, and an encrypted private key file can be used after decrypted with user password. If a password is exposed to hackers, hacker decrypt the encrypted private key file, and uses it. For this reason, the hacker attacks user equipment in a various way like installing Trojan's horse to take over the user's certificate and private key file. In this paper, I propose the management method to secure private key of PKI using One Time Password certification technique. As a result, even if the encrypted private key file is exposed outside, the user's private key is kept safely.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2003.12a
• /
• pp.611-614
• /
• 2003

S.S.Al-Riyami와 K.G.Paterson에 의해 제안된 Certificate-less 공개키 암호 시스템은 기존 공개키 암호 시스템이 가지는 인증서 관리의 불편함과 ID-based 암호 시스템이 가지는 Key Escrow문제를 동시에 해결해 주었다. 하지만 대부분의 공개키 암호 시스템 과 마찬가지로 Certificate-less 공개키 암호 시스템 역시 비공개키의 노출에 대한 문제를 가지고 있다. 따라서 본 논문에서는 기존 Certificate-less 공개키 암호 시스템에 Strong Key Insulation을 제공함으로써 보다 안전한 암호 시스템을 제안한다. 또한 이 시스템은 기존 Key Insulated 공개키 암호 시스템에 비해 계산량을 줄임으로써 보다 효율적인 암호 시스템을 구축할 수 있다.

• Proceedings of the Korea Information Assurance Society Conference
• /
• 2004.05a
• /
• pp.77-82
• /
• 2004

The notion of a certificate was introduced by Kohnfelder in his 1978 MIT bachelor's thesis. The idea, now common, was that a certificate is a digitally signed statement binding the key-holder's name to a public key. With the increasing acceptance of digital certificate, there has been a gaining impetus for methods to nullify the compromised digital certificates and enable the end user to receive this information before be trusts a revoked certificate. The problem of certificate revocation is getting more and more crucial with the development of wide spread PKIs. In this paper, we investigate recent trend of certificate revocation mechanism.

• Journal of Internet Computing and Services
• /
• v.7 no.3
• /
• pp.83-91
• /
• 2006

In this paper, we improved a cryptography system model based on the secure initial authentication public key with PKINIT of authentication and key recovery protocol. It is applied to all fields of cryptography system using certificate. This study presents two mechanisms to authenticate between member users. The first mechanism is initial authentication and distribution of session key by public key cryptography based on certificate between entity and server, and the second mechanism is a key recovery support protocol considering loss of session key in the secure communication between application servers.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.10 no.2
• /
• pp.3-12
• /
• 2000

In this paper we propose a new algorithm which resolves the inconsistency problems occurring when DNS severs are employed as elements of PKI. The inconsistency may take place between primary name servers and secondary name servers and between cached certificate and original certificate. The former can be removed by adapting RFC 1996 NOTIFY opcode for DNS. In order to eliminate the latter type of inconsistency we develope a new algorithm which is implemented with two additional RR(Resource Record). The present algorithm is designed such that DNS contacts the destination DNS prior to returning public key to users. Therefore the inconsistency problem occurring when DNS is operated as PKI can be eliminated by using the proposed adaptation and algorithm.

• Proceedings of the Korea Society of Information Technology Applications Conference
• /
• 2005.11a
• /
• pp.277-280
• /
• 2005

With the proliferation of mobile terminals, use of the Internet in mobile environments is becoming more common. To support mobility in these terminals, Mobile IPv4 is proposed and represents the standard in IPv4 environments. Authentication should be mandatory, because mobile terminals can utilize Internet services in any foreign domain. Mobile IPv4 provides symmetric key based authentication using the default HMAC-MD5. However, symmetric key based authentication creates a key distribution problem. To solve this problem, public key based authentication mechanisms have been proposed. In this paper, the performance of each of these mechanisms is evaluated. The results present that, among these mechanisms, partial certificate based authentication has superior performance, and certificate based authentication has the worst performance. Although current public key based authentication mechanisms have lower performance than symmetric key based authentication, this paper presents the possibility that public key based authentication mechanisms may be used for future mobile terminal authentication.

• The Journal of Society for e-Business Studies
• /
• v.4 no.2
• /
• pp.23-40
• /
• 1999

Nowadays, major application of public key certification technology based on PKI(Public Key Infrastructure) is electronic commerce. Public key certification technology may include various sub-technologies such as key recovery, secret sharing, certificate/key management, and directory system technology. This thesis discusses PKI-based certification authority technology for electronic commerce on the Internet.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.12
• /
• pp.3352-3365
• /
• 2012

Group key agreement (GKA) is a cryptographic primitive allowing two or more users to negotiate a shared session key over public networks. Wu et al. recently introduced the concept of asymmetric GKA that allows a group of users to negotiate a common public key, while each user only needs to hold his/her respective private key. However, Wu et al.'s protocol can not resist active attacks, such as fabrication. To solve this problem, Zhang et al. proposed an authenticated asymmetric GKA protocol, where each user is authenticated during the negotiation process, so it can resist active attacks. Whereas, Zhang et al.'s protocol needs a partially trusted certificate authority to issue certificates, which brings a heavy certificate management burden. To eliminate such cost, Zhang et al. constructed another protocol in identity-based setting. Unfortunately, it suffers from the so-called key escrow problem. In this paper, we propose the certificateless authenticated asymmetric group key agreement protocol which does not have certificate management burden and key escrow problem. Besides, our protocol achieves known-key security, unknown key-share security, key-compromise impersonation security, and key control security. Our simulation based on the pairing-based cryptography (PBC) library shows that this protocol is efficient and practical.

• Proceedings of the Korea Contents Association Conference
• /
• 2005.05a
• /
• pp.91-96
• /
• 2005

Recetly, the term Personal Public Key Infrastructure (PKI) was introduced to supprot reliable and authenticated service in a Personal Area Network (PAN). However, traditional public key signature schemes and certificate status management are not suitable for a PAN environment since mobile devices that constitute the PAN have limited computing capability. In this paper, we propose a new scheme that efficiently provides signature generation and certificate status management for mobile devices. Based on hash chain technique, we intend to reduce computational overhead on signature generation, and further, to minimize communication overhead for managing certificate status.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.3
• /
• pp.1246-1259
• /
• 2015

Certificate-based signature (CBS) combines the advantages of both public key-based signature and identity-based signature, while saving from the disadvantages of drawbacks in both PKS and IBS. The insecure deployment of CBS under the hostile circumstances usually causes the exposure of signing key to be inescapable. To resist the threat of key leakage, we present a pairing-free key insulated CBS scheme by incorporating the idea of key insulated mechanism and CBS. Our scheme eliminates the costly pairing operations and as a matter of fact outperforms the existing key insulated CBS schemes. It is more suitable for low-power devices. Furthermore, the unforgeability of our scheme has been formally proven to rest on the discrete logarithm assumption in the random oracle model.