The growing popularity of web applications in the last few years has led users to give the management of their data to online application providers, which will endanger the security and privacy of the users. In this paper1 , we present WebIBC, which integrates public key cryptography into web applications without any browser plugins. The public key of WebIBC is provided by identity based cryptography, eliminating the need of public key and certificate online retrieval; the private key is supplied by the fragment identifier of the URL inspired by BeamAuth [6]. The implementation and performance evaluation demonstrate that WebIBC is secure and efficient both in theory and practice.