Threshold cryptosystem based on factoring and discrete logarithm problems

Recently, the development of cryptosystem based on two problems has increased, since it is proved that the cryptosystem based on two problems is more secure than the cryptosystem based on single problem. Meanwhile, the concept of group-oriented cryptography, known as threshold cryptography, gave a new dimension in development of cryptosystems. In this paper we propose a new threshold cryptosystem based on two number theoretical problems; factoring and discrete logarithms. Other than the scheme, we also show that our cryptosystem is secure against some possible attack and requires reasonable time in encryption and decryption phases.