Due to the rapid development of smart-phones, mobile commerce becomes very popular and valuable. The communication and information security of the mobile commerce is heavily dependent on the public key cryptosystems such as RSA. However, existing public key cryptosystems are not available for the resource constrained devices like smart-phone. Therefore, the new elliptic curve cryptosystem with very low cost as compared to RSA is useful and suggested for mobile commerce. The polynomial basis multiplication is the most important arithmetic operation in the elliptic curve cryptosystem. A new and proved effective cryptanalysis is called fault based cryptanalysis. To protect such type cryptanalysis, the simple way is to redesign cryptosystems with concurrent error detection capability and only output error-free computed results. The polynomial basis multipliers generated by trinomials have advantages of low complexity and easy VLSI implementation. However, no existing polynomial basis multipliers which are generated by trinomials have concurrent error detection capability. Thus, a new polynomial basis multiplier using trinomial with concurrent error detection capability will be presented. As compared to other existing polynomial basis multipliers using general polynomials, the proposed polynomial basis multiplier using trinomial with concurrent error detection capability saves about 40% space complexity.