A New Rabin-type Trapdoor Permutation Equivalent to Factoring

Public key cryptography has been invented to overcome some key management problems in open networks. Although nearly all aspects of public key cryptography rely on the existence of trapdoor one-way functions, only a very few candidates for this primitive have been observed yet. In this paper, we introduce a new trapdoor one-way permutation based on the hardness of factoring integers of p2q-type. We point out that there are some similarities between Rabin's trapdoor permutation and our proposal. Although our function is less efficient, it possesses a nice feature which is not known for modular squaring, namely there is a variant with a different and easy-to-handle domain. Thus it provides some advantages for practical applications. To confirm this statement, we develop a simple hybrid encryption scheme based on our proposed trapdoor permutation that is CCA-secure in the random oracle model.