WTLS (Wireless Transport Layer Security) is an important standard protocol for secure wireless access to Internet services. WTLS employs public-key cryptosystems during the handshake between mobile client and WAP gateway (server). Several cryptosystems at different key strengths can be used in WTLS. The trade-off is security versus processing and transmission time. In this paper, an analytical performance model for public-key cryptosystem operations in WTLS protocol is developed. Different handshake protocols, different cryptosystems and key sizes are considered. Public-key cryptosystems are implemented using state-of-the–art performance improvement techniques, yielding actual performance figures for individual cryptosystems. These figures and the analytical model are used to calculate the cost of using public-key cryptosystems in WTLS. Results for different cryptosystems and handshake protocols are comparatively depicted and interpreted. It has been observed that ECC (Elliptic Curv...