An identity based beta cryptosystem

In a modern open network system, data security technologies such as cryptosystems, signature schemes, etc., are indispensable for reliable data transmission. In particular, for a large-scale network, ID-based systems such as the ID-based cryptosystem, the ID-based signature scheme, or the ID-based key distribution system are among the better countermeasures for establishing efficient and secure data transmission systems. The concept of an ID-based cryptosystem has been proposed by Shamir [1], and it is advantageous to public-key cryptosystems because a large public-key file is not required for such a system. This paper proposes an ID-based beta cryptosystem under the security assumptions of the generalized discrete logarithm problem and integer factorization problem, which is one of the earliest realizations in Shamir´s sense. Furthermore, we consider the security against a conspiracy of some users in the proposed system, and show the possibility of establishing a more secure system.