Identity-based public key encryption (short for IBE) system can directly take user's ID as her public key, without need of public key certificate. Comparing to the traditional PKI, IBE is easy to develop and deploy with lower cost. It is specially suited for the enterprises with centralized key management supported. In this paper, a web servicebased IBE key management service system, IBE Service, is firstly proposed, which facilitates users of different security domains to manage IBE keys and provides a user secure policy-centered key service. Based on IBE service, a general file encryption client application is then developed. It utilizes SOAP protocol to implement XML-based IBE key data communications. The proposed new file encryption system can map the receiver's ID as her public key, and the receiver can automatically do decryption by achieving her private key from IBE service. It is more secure, efficient, as well as with flexible ID secure policy supported.