모바일 환경에서 Fiat-Shamir방식을 적용한 안전한 그룹키 갱신 메커니즘

Abstract

The number of remote, computer-based conferences have been increasing, and the supply of mobile terminals and the use of Mobile Radio Communication have been increasing in an alarming way. Simultaneously, the requirement for securing safe communication channels also has been steadily increasing . In order to protect the terminals from the illegal use, technologies that keep off the surreptitious use of conversation and protect the legal terminal by utilizing formal identification have been developed. In this paper, we proposed an improved scheme for renewing and distributing a group key in order to secure the safety of the remote conferences and digital mobile communication systems. It is a security service based on the group key which is necessary for encryption and authentication. It is an efficient and safe scheme for renewing and distributing a group key by using a digital signature and a key distribution scheme based on a secure ID technique. The proposed protocol is so designed as to create a new secret key within the group when the center wants to renew the group key for any reason, when the terminal losses the group key or the secret information, when any user losses their terminal, or when the center wants to exclude specific terminals from the security service. For example, in the case of excluding a specific terminal from the group, the protocol must be able to keep off illegal tapping or the surreptitious use of the conversation from the excluded terminal. Therefore, in this case, the key distribution center must re-share the group key as fast as possible and must make normal communication possible and must have no influence upon the existing communication and must prevent the excluded terminal from intercepting the new group key when re-sharing it. The proposed protocol can keep off the illegal change of the transmission information and illegal key renewal because it employs the safety scheme based on the ID-based key distribution scheme and Fiat-Shamir's digital signature. In particular, while the existing scheme can be disclosed to the various attacks, our protocol can cope with them because it adds a digital signature. Also it can prevent the transmission information from being changed or can verify the authority of the digital signature of the center that this information is transmitted by the key distribution center. The proposed protocol doesn't have more distinguished advantages about an amount of computation and the number of communications than the existing one. However, it can be effectively managed even if the terminals have small storage capacity and computing power, and can consecutively renew the group key more than two times. Even if many terminals are simultaneously excluded from the group, the center can reflect the various changes and can create the secret information in a lump and can handle the various changes at once. It can easily renew the group key when it intends to alter the group key without the change of terminals.