The Globus Security Infrastructure (GSI) is one of the most famous security architecture. GSI is based on Public Key Infrastructure (PKI), which performs mutual authentication via X.509 certificates. We present a password-based grid security infrastructure (PBGSI), which authenticates clients by authenticated key exchange (AuthA) methods and uses improved Chaffing and Winnowing protocol for secure data transfer. By using password-based methods in authentication, authorization and delegation, PBGSI provides convenient interface for the user. At the same time, encryption-less secure data transfer improves the performance; and mechanisms used in our scheme (time-stamp etc.) enhance the security of the whole grid.