A key escrow system of the RSA cryptosystem

This paper focuses a key escrow system of the RSA cryptosystem that protects user privacy with the following properties; (1) neither investigation agency nor key escrow agent accesses private key of user directly, (2) investigation agency can decrypt user data of restricted time period and communication entities, and (3) split private keys of user are deposited correctly in multiple key escrow agents without any information leakage of the private key with help of a zero-knowledge interactive protocol. The security of the whole system is discussed as well as the performance of the zero-knowledge interactive protocol.